Updated June 10th, 2019.
PC users are accustomed to using their mice to “right-click,” generating a little menu of possibilities depending on what they clicked on, like so:
We can do that too, even though Apple mice come with just one button.* Just hold the Control key down (either one) and then click. Try control-clicking icons on the desktop, words in web pages, photos in Photos, and songs in iTunes. Handy.
Control-click works with trackpads too.
*Technically, the Apple mouse knows where your finger is when you click. If you’ve used the Mouse preference pane to set up a “secondary click” for the right side of the mouse you can right-click like the PC guys. Personally, I like the Control-click method as it’s more of a sure-thing. Your finger is never in the wrong place if you Control-click.