How to | Find Information about Functions
The Wolfram System provides several convenient ways to find information about functions. In addition to searching the documentation or navigating the guide pages, you can access documentation on functions directly from within your notebook.
You can also do this with the keyboard shortcut that is listed next to Find Selected Function. In either case, you will be taken directly to the function page for the function that you have highlighted. Using the keyboard shortcut is a convenient way to access function pages while you are working in a notebook.
Another way to access information about functions from within a notebook is to evaluate the function with a question mark preceding it. You get the usage message that is at the top of the function page. You can click >> to open the full function page: