diff --git a/src/ui.rs b/src/ui.rs
index 34be178..36ca508 100644
--- a/src/ui.rs
+++ b/src/ui.rs
@@ -3,9 +3,10 @@ use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
 use ratatui::{
     prelude::*,
     widgets::*,
-    Frame,
+    style::{Color, Modifier, Style},
+    text::{Line, Span, Text},
+    layout::{Alignment, Constraint, Direction, Layout, Rect},
 };
-use std::borrow::Cow;
 
 pub struct App<'a> {
     pub sessions: &'a [SMTPSession],
@@ -16,6 +17,7 @@ pub struct App<'a> {
     filter_type: Option<FilterType>,
     filter_text: String,
     pub log_display_mode: LogDisplayMode,
+    pub show_help: bool,
 }
 
 #[derive(PartialEq)]
@@ -42,6 +44,7 @@ impl<'a> App<'a> {
             filter_type: None,
             filter_text: String::new(),
             log_display_mode: LogDisplayMode::SingleLine,
+            show_help: false,
         }
     }
 
@@ -81,6 +84,12 @@ impl<'a> App<'a> {
     }
 
     pub fn on_key(&mut self, key: KeyEvent) {
+        // If help is shown, any key should close it
+        if self.show_help {
+            self.show_help = false;
+            return;
+        }
+
         match key.code {
             KeyCode::Char('q') => self.should_quit = true,
             KeyCode::Char('c') if key.modifiers.intersects(KeyModifiers::CONTROL) => self.should_quit = true,
@@ -181,12 +190,61 @@ impl<'a> App<'a> {
                     self.selected_session = Some(self.filtered_sessions[0]);
                 }
             }
+            KeyCode::Char('h') => {
+                self.show_help = !self.show_help;
+            }
             _ => {}
         }
     }
 }
 
+fn render_help(f: &mut Frame, area: Rect) {
+    let block = Block::default()
+        .title(" Help ")
+        .borders(Borders::ALL)
+        .border_style(Style::default().fg(Color::Yellow));
+
+    let text = vec![
+        Line::from("Navigation:".bold()),
+        Line::from("  ↑/↓    - Move selection up/down"),
+        Line::from("  PgUp/PgDn - Move by 10 entries"),
+        Line::from("  Home/End - Jump to first/last entry"),
+        Line::from("  j/k     - Scroll log view up/down"),
+        Line::from(""),
+        Line::from("Filtering:".bold()),
+        Line::from("  f       - Filter by sender"),
+        Line::from("  t       - Filter by recipient"),
+        Line::from("  r       - Reset filter"),
+        Line::from("  <text>  - Type to filter"),
+        Line::from("  Enter   - Apply filter"),
+        Line::from("  Esc     - Cancel filter"),
+        Line::from(""),
+        Line::from("View:".bold()),
+        Line::from("  l       - Toggle log display mode (single/multi-line)"),
+        Line::from("  h       - Toggle this help"),
+        Line::from(""),
+        Line::from("Quit:".bold()),
+        Line::from("  q       - Quit"),
+        Line::from("  Ctrl+c  - Quit"),
+        Line::from(""),
+        Line::from("Usage:".bold()),
+        Line::from("  postfix-log-viewer [FILE]..."),
+        Line::from("  postfix-log-viewer mail.log mail.log.1.gz"),
+    ];
+
+    let paragraph = Paragraph::new(text)
+        .block(block)
+        .alignment(Alignment::Left);
+
+    f.render_widget(paragraph, area);
+}
+
 pub fn ui(f: &mut Frame, app: &App) {
+    if app.show_help {
+        render_help(f, f.size());
+        return;
+    }
+
     let chunks = Layout::default()
         .direction(Direction::Horizontal)
         .constraints([Constraint::Percentage(40), Constraint::Percentage(60)].as_ref())