# Displaying and modifying variables

The Variables tab in the Debugger displays the names and values of any global and Timeline variables in the movie. If you change the value of a variable on the Variables tab, you can see the change reflected in the movie while it runs. For example, to test collision detection in a game, you could enter the variable value to position a ball in the correct location next to a wall.

The Locals tab in the Debugger displays the names and values of any local variables that are available wherever the movie has stopped at a breakpoint or anywhere else within a user-defined function.

To display a variable:

1. Select the movie clip containing the variable from the display list.

To display global variables, select the `_global` clip in the display list.

2. Click the Variables tab.

The display list updates automatically as the movie plays. If a movie clip is removed from the movie at a specific frame, that movie clip, along with its variable and variable name, is also removed from the display list in the Debugger. However, if you mark a variable for the Watch list, that variable is not removed.

To modify a variable value:

Double-click the value and enter a new value.

The value cannot be an expression. For example, you can use "`Hello"`, `3523`, or "`http://www.macromedia.com"`, and you cannot use `x + 2` or `eval("name:" +i)`. The value can be a string (any value surrounded by quotation marks), a number, or a Boolean value (`true` or `false`).

Note: To write the value of an expression to the Output window in test mode, use the `trace` action. See Using the trace action.