diff --git a/src/actions.rs b/src/actions.rs
index 1e7e98f..338fef3 100644
--- a/src/actions.rs
+++ b/src/actions.rs
@@ -19,7 +19,7 @@
 
 use std::collections::HashMap;
 
-use crate::{Direction, InsertState, Mode, State};
+use crate::{Direction, InsertState, Mode, NormalState, State};
 
 pub type Action = fn(&mut State);
 
@@ -55,6 +55,37 @@ pub fn move_line_up(state: &mut State) {
     state.move_cursor(Direction::Up);
 }
 
+pub fn page_up(state: &mut State) {
+    state.set_error("page_up is unimplemented");
+}
+
+pub fn page_down(state: &mut State) {
+    state.set_error("page_down is unimplemented");
+}
+
+pub fn goto_line_start(state: &mut State) {
+    state.set_error("goto_line_start is unimplemented");
+}
+
+pub fn goto_line_end_newline(state: &mut State) {
+    state.set_error("goto_line_end_newline is unimplemented");
+}
+
+pub fn normal_mode(state: &mut State) {
+    match state.mode {
+        Mode::Insert(InsertState { append: true }) => {
+            state.move_cursor(Direction::Left);
+        }
+        _ => {}
+    }
+
+    state.mode = Mode::Normal(NormalState::default());
+}
+
+pub fn visual_mode(state: &mut State) {
+    state.mode = Mode::Visual;
+}
+
 pub fn insert_mode(state: &mut State) {
     state.mode = Mode::Insert(InsertState { append: false });
 }
@@ -63,6 +94,14 @@ pub fn append_mode(state: &mut State) {
     state.mode = Mode::Insert(InsertState { append: true });
 }
 
+pub fn insert_at_line_start(state: &mut State) {
+    state.set_error("insert_at_line_start is unimplemented");
+}
+
+pub fn insert_at_line_end(state: &mut State) {
+    state.set_error("insert_at_line_end is unimplemented");
+}
+
 pub fn open_below(state: &mut State) {
     state.cursor.line += 1;
     state.cursor.column = 0;
@@ -75,3 +114,26 @@ pub fn open_above(state: &mut State) {
     state.buffer.insert_char(state.cursor, '\n');
     state.mode = Mode::Insert(InsertState { append: false });
 }
+
+pub fn undo(state: &mut State) {
+    state.set_error("undo is unimplemented");
+}
+
+pub fn redo(state: &mut State) {
+    state.set_error("redo is unimplemented");
+}
+
+pub fn delete_char_backward(state: &mut State) {
+    state.move_cursor(Direction::Left);
+    state.buffer.remove(state.cursor);
+}
+
+pub fn delete_char_forward(state: &mut State) {
+    state.buffer.remove(state.cursor);
+}
+
+pub fn insert_newline(state: &mut State) {
+    state.buffer.insert_char(state.cursor, '\n');
+    state.cursor.line += 1;
+    state.cursor.column = 0;
+}
diff --git a/src/main.rs b/src/main.rs
index f2f5240..8dad9b4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -192,6 +192,13 @@ impl State {
         Ok(())
     }
 
+    /// Sets the state to `Mode::Normal` with an error message.
+    pub fn set_error(&mut self, error: impl ToString) {
+        self.mode = Mode::Normal(NormalState {
+            error: Some(error.to_string()),
+        });
+    }
+
     pub fn on_event(&mut self, event: Event) {
         match &self.mode {
             Mode::Normal(state) => self.on_normal_event(event, state.clone()),