As a choral musician, and ever increasing availability of world music, I often find the need to type in names of songs (or lyrics) that contain special accents. In Windows, I always had to go to the key map and insert accents. In earlier versions of Mac OS X, it was possible to hit various keys (alt, option, command) with letter keys to enter accents. Still, knowing which keystrokes to use (if you didn’t use them daily) could be difficult to keep straight.
Can’t remember which key combination creates an e with an accent agu (é)? Press and hold a key to bring up accented alternatives, a feature introduced in iOS. You can click the accent you want, or, since your fingers are already on the keyboard, press the number that appears below the character you want.