How can I check which version of Angular I'm using?

For Angular 1 or 2 (but not for Angular 4+) :

you can also open the console on the developer tools of whatever browser you use and type angular.version to access the Javascript object that holds angular version.

Very useful when the script is minified with no header comment.

Edit: When this answer was written, there was only AngularJS 1.x. Look in the answers below for Angular versions >= 2.

AngularJS does not have a command line tool.

You can get the version number from the JavaScript file itself.

Header of the current angular.js:

/**
 * @license AngularJS v1.0.6
 * (c) 2010-2012 Google, Inc. http://angularjs.org
 * License: MIT
 */

For Angular 2+, in any modern browser having developper tools (F12) you can inspect the top level application tag.

For Internet Explorer 11 or Edge you can find information here :

Works for Angular 2+ Chrome browser

Firefox firebug