A "context" menu changes depending on where it is used ("context"), they are generally invoked with a right-click. You are aware that you can click on some things to get certain choices, but that is kind of hit and miss learning. Now you will be a little more aware of some of the places you can actually click on and what to expect. You will get a different menu or variations depending on what/where you right-click on. Some places where you might click on things. # On a tool-bar button # On an entry area in the tools bar # On the Tabs Back/Forward button (instead of the drop-down) # In the body of an HTML with nothing select or pointed at. # On a word or text, or a selection that includes a word(s) or text # On a link, or a selection that includes a link(s) # On an image, or a selection that includes an image Extensions will add things to menus, context menus, toolbars, style, etc. It may be a little old (much of it 7 years old) but you can see the concept and how the context menu changes changes, * http://dmcritchie.mvps.org/firefox/rightff.htm '''Context menu''' definitions: * context menu - Ask.com Search<br>http://ask.reference.com/web?q=context%20menu&amp;l=dir&amp;qsrc=2891&amp;o=10616 * http://education.yahoo.com/reference/dictionary/search?p=context%20menu<br>http://education.yahoo.com/reference/dictionary/search?p=context%20menu * Context menu - Wikipedia, the free encyclopedia<br>http://en.wikipedia.org/wiki/Context_menu If you want to understand menus a bit better and change the order and include menu separators install the "'''Menu Editor'''" extension https://addons.mozilla.org/firefox/addon/menu-editor/

"tab context menu" is probably referring to when you right-click and Tab and "main context menu" is probably referring to when you right-click in a blank part in a Firefox window.