Search is located in the main navigation, but you can open it using the CTRL + S shortcut (CTRL + ALT + S for Windows and Linux).
It helps you easily find anything in your account. It can be a deal, a task, a project, a person, a company...
Just start typing the phrase you're looking for and you'll get search results that match your phrase the best.
If you still haven't find what you've been looking for, go the bottom of the search results and search for the phrase across your entire account.