A sure-fire way to prevent your Mac from slowing down and avoid errors like "Your startup disk is almost full" is to ...

Your iPhone may have low storage because it's been consumed by System Data, which can potentially consume all available capacity. Here's how to regain space when things get too bloated to function.

If you are struggling with not enough storage and trying to make more space on your Mac, Apple helpfully outlines ways to save space and shows some mysteriously named elements taking up storage space.