diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4fedd09..47480df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,13 +7,14 @@
     - `t` now truncates the file (it was `T` before).
     - `T` reverse truncates the file (deletes from offset 0 to current offset).
     - Both commands above need confirmation from the user as they can't be undone.
-  - Selection mode: 
+  - Selection mode:
     - Bug fix: selection no longer disappears when selected range is bigger than page size.
+    - Users can now mark colored blocks with `Alt-m`. Press multiple times to change colors. `[` and `]` keys navigate to marked block boundaries.
 
 ## dz6 v0.6.0
 
 - Hex view:
-  -  `Ctrl+f` goes down one page (same as `PgDown`).
+  - `Ctrl+f` goes down one page (same as `PgDown`).
   - `Ctrl+b` goes up one page (same as `PgUp`).
   - `~` changes case when applicable (available in Normal, Replace, and Select modes).
   - `Ctrl+a`, `Ctrl+x`, `n`, and `z` work without putting the editor in Replace mode.
@@ -57,25 +58,25 @@
 - Basic support for multibyte selection. Press `v` (like visual mode in vim), then select a byte range. Then, `y` to copy bytes to clipboard, `z` to fill them with zeroes, or `n` to fill them with x86 NOPs.
 - Support for initialization file at `$HOME/.gdbinit`. Commands added to this file will be executed at startup (one per line). (https://github.com/mentebinaria/dz6/issues/12)
 - New `:` commands:
-    - `set db` turn on database loading/saving (default)
-    - `set nodb` turn off the above
+  - `set db` turn on database loading/saving (default)
+  - `set nodb` turn off the above
 
 ## dz6 v0.4.0
 
 - Status bar now shows "COMMAND" when you press `:`.
 - New `:` commands:
-    - `cmt <offset> <comment>` (programatic alternative to `;`)
-    - `set byteline <number>` sets the number of bytes per line in the hex dump
-    - `set ctrlchar <char>`sets the character shown for ASCII non-graphical byte values
-    - `set dimzero` dim nullbytes
-    - `set dimctrl` dim all control characters
-    - `set nodim` turn off dimming
-    - `set theme` changes the theme
-    - `w` write changes to file
-    - `wq` or `x` write changes to file and quit
+  - `cmt <offset> <comment>` (programatic alternative to `;`)
+  - `set byteline <number>` sets the number of bytes per line in the hex dump
+  - `set ctrlchar <char>`sets the character shown for ASCII non-graphical byte values
+  - `set dimzero` dim nullbytes
+  - `set dimctrl` dim all control characters
+  - `set nodim` turn off dimming
+  - `set theme` changes the theme
+  - `w` write changes to file
+  - `wq` or `x` write changes to file and quit
 - In-memory buffer when patching bytes. Nothing is written to the file until you use some of the writing commands (`w`, `wq` or `x`), but truncating is an exception (`T` in replace mode).
- - Light theme.
-- dz6 beeps if you try  to enter replace mode when editing a read-only file.
+- Light theme.
+- dz6 beeps if you try to enter replace mode when editing a read-only file.
 
 ## dz6 v0.3.1
 
diff --git a/Cargo.lock b/Cargo.lock
index a7cf670..f850eba 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -180,6 +180,17 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
+[[package]]
+name = "chacha20"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f8d983286843e49675a4b7a2d174efe136dc93a18d69130dd18198a6c167601"
+dependencies = [
+ "cfg-if",
+ "cpufeatures 0.3.0",
+ "rand_core 0.10.1",
+]
+
 [[package]]
 name = "clap"
 version = "4.6.1"
@@ -267,6 +278,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b2a41393f66f16b0823bb79094d54ac5fbd34ab292ddafb9a0456ac9f87d201"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crossterm"
 version = "0.29.0"
@@ -448,6 +468,7 @@ dependencies = [
  "hex",
  "memchr",
  "mmap-io",
+ "rand 0.10.1",
  "ratatui",
  "regex",
  "serde",
@@ -559,6 +580,30 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"
 
+[[package]]
+name = "futures-core"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e3450815272ef58cec6d564423f6e755e25379b217b0bc688e295ba24df6b1d"
+
+[[package]]
+name = "futures-task"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "037711b3d59c33004d3856fbdc83b99d4ff37a24768fa1be9ce3538a1cde4393"
+
+[[package]]
+name = "futures-util"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "389ca41296e6190b48053de0321d02a77f32f8a5d2461dd38762c0593805c6d6"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "pin-project-lite",
+ "slab",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.14.7"
@@ -611,6 +656,7 @@ dependencies = [
  "cfg-if",
  "libc",
  "r-efi 6.0.0",
+ "rand_core 0.10.1",
  "wasip2",
  "wasip3",
 ]
@@ -637,9 +683,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.17.0"
+version = "0.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4f467dd6dccf739c208452f8014c75c18bb8301b050ad1cfb27153803edb0f51"
+checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a"
 
 [[package]]
 name = "heck"
@@ -672,7 +718,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d466e9454f08e4a911e14806c24e16fba1b4c121d1ea474396f396069cf949d9"
 dependencies = [
  "equivalent",
- "hashbrown 0.17.0",
+ "hashbrown 0.17.1",
  "serde",
  "serde_core",
 ]
@@ -722,10 +768,12 @@ checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
 
 [[package]]
 name = "js-sys"
-version = "0.3.95"
+version = "0.3.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2964e92d1d9dc3364cae4d718d93f227e3abb088e747d92e0395bfdedf1c12ca"
+checksum = "67df7112613f8bfd9150013a0314e196f4800d3201ae742489d999db2f979f08"
 dependencies = [
+ "cfg-if",
+ "futures-util",
  "once_cell",
  "wasm-bindgen",
 ]
@@ -1143,7 +1191,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3c80231409c20246a13fddb31776fb942c38553c51e871f8cbd687a4cfb5843d"
 dependencies = [
  "phf_shared",
- "rand",
+ "rand 0.8.6",
 ]
 
 [[package]]
@@ -1168,6 +1216,12 @@ dependencies = [
  "siphasher",
 ]
 
+[[package]]
+name = "pin-project-lite"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
+
 [[package]]
 name = "portable-atomic"
 version = "1.13.1"
@@ -1226,7 +1280,18 @@ version = "0.8.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a"
 dependencies = [
- "rand_core",
+ "rand_core 0.6.4",
+]
+
+[[package]]
+name = "rand"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2e8e8bcc7961af1fdac401278c6a831614941f6164ee3bf4ce61b7edb162207"
+dependencies = [
+ "chacha20",
+ "getrandom 0.4.2",
+ "rand_core 0.10.1",
 ]
 
 [[package]]
@@ -1235,6 +1300,12 @@ version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 
+[[package]]
+name = "rand_core"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "63b8176103e19a2643978565ca18b50549f6101881c443590420e4dc998a3c69"
+
 [[package]]
 name = "ratatui"
 version = "0.30.0"
@@ -1474,7 +1545,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
 dependencies = [
  "cfg-if",
- "cpufeatures",
+ "cpufeatures 0.2.17",
  "digest",
 ]
 
@@ -1517,9 +1588,15 @@ dependencies = [
 
 [[package]]
 name = "siphasher"
-version = "1.0.2"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ee5873ec9cce0195efcb7a4e9507a04cd49aec9c83d0389df45b1ef7ba2e649"
+
+[[package]]
+name = "slab"
+version = "0.4.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b2aa850e253778c88a04c3d7323b043aeda9d3e30d5971937c1855769763678e"
+checksum = "0c790de23124f9ab44544d7ac05d60440adc586479ce501c1d6d7da3cd8c9cf5"
 
 [[package]]
 name = "smallvec"
@@ -1862,9 +1939,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.118"
+version = "0.2.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0bf938a0bacb0469e83c1e148908bd7d5a6010354cf4fb73279b7447422e3a89"
+checksum = "49ace1d07c165b0864824eee619580c4689389afa9dc9ed3a4c75040d82e6790"
 dependencies = [
  "cfg-if",
  "once_cell",
@@ -1875,9 +1952,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.118"
+version = "0.2.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eeff24f84126c0ec2db7a449f0c2ec963c6a49efe0698c4242929da037ca28ed"
+checksum = "8e68e6f4afd367a562002c05637acb8578ff2dea1943df76afb9e83d177c8578"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -1885,9 +1962,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.118"
+version = "0.2.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9d08065faf983b2b80a79fd87d8254c409281cf7de75fc4b773019824196c904"
+checksum = "d95a9ec35c64b2a7cb35d3fead40c4238d0940c86d107136999567a4703259f2"
 dependencies = [
  "bumpalo",
  "proc-macro2",
@@ -1898,9 +1975,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.118"
+version = "0.2.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5fd04d9e306f1907bd13c6361b5c6bfc7b3b3c095ed3f8a9246390f8dbdee129"
+checksum = "c4e0100b01e9f0d03189a92b96772a1fb998639d981193d7dbab487302513441"
 dependencies = [
  "unicode-ident",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 053fb68..fcab473 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,6 +20,7 @@ evalexpr = "13.1.*"
 hex = "0.4.3"
 memchr = "2.8.0"
 mmap-io = "0.9.4"
+rand = "0.10.1"
 ratatui = "0.30.0"
 regex = "1.11.2"
 serde = { version = "1.0.228", features = ["derive"] }
diff --git a/src/database.rs b/src/database.rs
index 7716f4a..80e593c 100644
--- a/src/database.rs
+++ b/src/database.rs
@@ -14,7 +14,10 @@ impl App {
         let target_db: PathBuf = target_dir.join(&cwd_db);
 
         // if there's nothing to be saved, delete any existing db files and return
-        if self.hex_view.bookmarks.is_empty() && self.hex_view.comment_name_list.is_empty() {
+        if self.hex_view.bookmarks.is_empty()
+            && self.hex_view.comment_name_list.is_empty()
+            && self.hex_view.blocks.is_empty()
+        {
             let _ = fs::remove_file(target_db);
             let _ = fs::remove_file(cwd_db);
             return Ok(());
diff --git a/src/hex/blocks.rs b/src/hex/blocks.rs
new file mode 100644
index 0000000..8b11712
--- /dev/null
+++ b/src/hex/blocks.rs
@@ -0,0 +1,32 @@
+use rand::prelude::*;
+use serde::{Deserialize, Serialize};
+
+#[derive(Default, Serialize, Deserialize, PartialEq, Eq, PartialOrd)]
+pub struct ColoredBlock {
+    pub start: usize,
+    pub end: usize,
+    pub bg_color: u32,
+    pub fg_color: u32,
+}
+
+fn get_random_color() -> u32 {
+    let mut rng = rand::rng();
+
+    rng.random::<u32>()
+}
+
+impl ColoredBlock {
+    pub fn new(start: usize, end: usize) -> Self {
+        ColoredBlock {
+            start,
+            end,
+            bg_color: get_random_color(),
+            fg_color: get_random_color(),
+        }
+    }
+
+    pub fn set_random_color(&mut self) {
+        self.bg_color = get_random_color();
+        self.fg_color = get_random_color();
+    }
+}
diff --git a/src/hex/draw.rs b/src/hex/draw.rs
index a784842..006174a 100644
--- a/src/hex/draw.rs
+++ b/src/hex/draw.rs
@@ -1,6 +1,7 @@
 use ratatui::{
     Frame,
     layout::{Constraint, Rect},
+    style::{Color, Style},
     widgets::{Cell, Clear, Row, Table},
 };
 
@@ -48,6 +49,7 @@ pub fn draw_hex_contents(app: &mut App, frame: &mut Frame, area: Rect) {
     let mut byte_row: Vec<Cell> = Vec::with_capacity(app.reader.page_current_size);
     let mut cell_hl_style = app.config.theme.highlight;
     let mut byte_style = app.config.theme.main;
+    let mut col_len = 2u16;
 
     let buffer = app.file_info.get_buffer();
     for (i, byte) in buffer
@@ -65,8 +67,6 @@ pub fn draw_hex_contents(app: &mut App, frame: &mut Frame, area: Rect) {
         byte_style =
             if app.state == UIState::HexSelection && app.hex_view.selection.contains(offset) {
                 app.config.theme.highlight
-            } else if app.hex_view.highlights.contains(byte) {
-                app.config.theme.byte_highlight
             } else if *byte == b'\0' && app.config.dim_zeroes {
                 app.config.theme.dimmed
             } else if !byte.is_ascii_graphic() && app.config.dim_control_chars {
@@ -81,6 +81,15 @@ pub fn draw_hex_contents(app: &mut App, frame: &mut Frame, area: Rect) {
             cell_hl_style = app.config.theme.highlight;
         }
 
+        for b in &app.hex_view.blocks {
+            if offset >= b.start && offset <= b.end {
+                byte_style = Style::new()
+                    .bg(Color::from_u32(b.bg_color))
+                    .fg(Color::from_u32(b.fg_color));
+                col_len = 3;
+            }
+        }
+
         if app.hex_view.changed_bytes.contains_key(&offset) {
             // typed chars in content instead of original ones
             byte_content = app.hex_view.changed_bytes[&offset].clone();
@@ -95,6 +104,11 @@ pub fn draw_hex_contents(app: &mut App, frame: &mut Frame, area: Rect) {
             }
         }
 
+        // byte highlight
+        if app.hex_view.highlights.contains(byte) {
+            byte_style = app.config.theme.byte_highlight;
+        }
+
         // TODO: column size (2) keep the separator char from being shown :(
         // if i > 0 && i % 4 == 0 {
         //     content.push(app.config.hex_mode_dword_separator);
@@ -123,11 +137,9 @@ pub fn draw_hex_contents(app: &mut App, frame: &mut Frame, area: Rect) {
         .select_column(Some(app.hex_view.cursor.x));
 
     // small trick to make selection looks better
-    let col_len = if app.state == UIState::HexSelection {
-        3
-    } else {
-        2
-    };
+    if app.state == UIState::HexSelection {
+        col_len = 3;
+    }
 
     let constraints = vec![Constraint::Length(col_len); app.config.hex_mode_bytes_per_line];
 
diff --git a/src/hex/events.rs b/src/hex/events.rs
index 3e9fdf3..a364650 100644
--- a/src/hex/events.rs
+++ b/src/hex/events.rs
@@ -21,7 +21,7 @@ pub fn hex_mode_events(app: &mut App, key: KeyEvent) -> Result<bool> {
             }
             ofs = ofs.saturating_add_signed(delta);
             // this is needed because it can start at 0,
-            // but it cannot be zero afterward
+            // but it cannot be zero afterwards.
             // without it, `O` doesn't work at offset 0
             if ofs == 0 {
                 app.goto(0);
@@ -336,6 +336,41 @@ pub fn hex_mode_events(app: &mut App, key: KeyEvent) -> Result<bool> {
                 crate::beep!(); // beep if there's nothing to undo
             }
         }
+        // set a new random color for a colored block
+        KeyCode::Char('m') => {
+            if key.modifiers.contains(KeyModifiers::ALT) {
+                for b in &mut app.hex_view.blocks {
+                    if app.hex_view.offset >= b.start && app.hex_view.offset <= b.end {
+                        b.set_random_color();
+                        break;
+                    }
+                }
+            }
+        }
+        // go to the nearest previous block boundary
+        KeyCode::Char('[') => {
+            for b in app.hex_view.blocks.iter().rev() {
+                if b.end < app.hex_view.offset {
+                    app.goto(b.end);
+                    break;
+                } else if b.start < app.hex_view.offset {
+                    app.goto(b.start);
+                    break;
+                }
+            }
+        }
+        // go to the nearest next block boundary
+        KeyCode::Char(']') => {
+            for b in &app.hex_view.blocks {
+                if b.start > app.hex_view.offset {
+                    app.goto(b.start);
+                    break;
+                } else if b.end > app.hex_view.offset {
+                    app.goto(b.end);
+                    break;
+                }
+            }
+        }
         _ => {}
     }
     Ok(false)
diff --git a/src/hex/hex_view.rs b/src/hex/hex_view.rs
index fda574f..edd02df 100644
--- a/src/hex/hex_view.rs
+++ b/src/hex/hex_view.rs
@@ -4,7 +4,7 @@ use ratatui::widgets::{ListState, TableState};
 use serde::{Deserialize, Serialize};
 use tui_input::Input;
 
-use crate::hex::comment::Comment;
+use crate::hex::{blocks::ColoredBlock, comment::Comment};
 
 // used in hex view struct to track the cursor position
 #[derive(Default, Debug)]
@@ -13,10 +13,12 @@ pub struct Point {
     pub y: usize,
 }
 
-#[derive(Default, Debug, Serialize, Deserialize)]
+#[derive(Default, Serialize, Deserialize)]
 pub struct HexView {
     #[serde(skip)]
     pub ascii_state: TableState,
+    // blocks are ByteBlock structs -- ranges with different colors
+    pub blocks: Vec<ColoredBlock>,
     pub bookmarks: Vec<usize>,
     #[serde(skip)]
     pub changed_bytes: HashMap<usize, String>,
diff --git a/src/hex/mod.rs b/src/hex/mod.rs
index 5750988..9f62a03 100644
--- a/src/hex/mod.rs
+++ b/src/hex/mod.rs
@@ -1,3 +1,4 @@
+pub mod blocks;
 pub mod comment;
 pub mod draw;
 pub mod edit;
diff --git a/src/hex/selection.rs b/src/hex/selection.rs
index 7ff6a5a..31f025d 100644
--- a/src/hex/selection.rs
+++ b/src/hex/selection.rs
@@ -1,8 +1,10 @@
+use crossterm::event::KeyModifiers;
 use ratatui::crossterm::event::{KeyCode, KeyEvent};
 use std::io::Result;
 
 use crate::app::App;
 use crate::editor::UIState;
+use crate::hex::blocks::ColoredBlock;
 
 #[derive(Debug, PartialEq, Clone, Copy)]
 pub enum Direction {
@@ -197,6 +199,27 @@ pub fn select_events(app: &mut App, key: KeyEvent) -> Result<bool> {
             app.state = UIState::Normal;
             app.hex_view.selection.clear();
         }
+        // set a random color for an existing block or create a new one
+        KeyCode::Char('m') => {
+            if key.modifiers.contains(KeyModifiers::ALT) {
+                for b in &mut app.hex_view.blocks {
+                    if app.hex_view.offset >= b.start && app.hex_view.offset <= b.end {
+                        b.set_random_color();
+                        app.state = UIState::Normal;
+                        return Ok(true);
+                    }
+                }
+                app.hex_view.blocks.push(ColoredBlock::new(
+                    app.hex_view.selection.start,
+                    app.hex_view.selection.end,
+                ));
+
+                // sorting is needed to [] and {} keys work correctly
+                app.hex_view.blocks.sort_by_key(|k| k.start);
+
+                app.state = UIState::Normal;
+            }
+        }
         _ => {}
     }