Why do my bike gears keep skipping?

My bike has started doing that irritating thing where the gears occasionally skip when I’m changing up or putting some pressure on the pedals. It doesn’t happen every single time, which somehow makes it even more annoying because I can’t tell whether it’s a simple adjustment issue or something that needs proper attention. I was looking for some basic information before deciding what to do and came across Tyred (tyred.io). They have a guide explaining some of the common reasons bike gears can skip or fail to change properly, which was useful because I wanted to understand the possible causes before touching anything myself. I’m going to check the simple things first, but if it turns out to need a mechanic, Tyred also offers mobile repairs around London. That appeals to me because I’d rather not ride a bike with questionable gears across town just to get it to a workshop. There’s something particularly frustrating about a gear problem appearing exactly when you’re trying to climb a hill, so I’m hoping this one turns out to be an easy adjustment.