The way you scroll and zoom in and out of documents
Your Mac is configured to allow you to zoom in and out of images and web pages by either pinching and unpinching with two fingers or by tapping the trackpad with two fingers to activate what Apple calls ‘Smart Zoom’. That can be very useful, but can also be confusing if, say, you tend to leave your thumb resting on the trackpad. To switch off this behaviour, tap on the Scroll & Zoom tab in the Trackpad System Preferences pane and uncheck the second and third boxes. If you don’t want to rotate an image with your fingers on the trackpad, turn that off, too.