[omaranto]

If informal descriptions confuse you, skip them and read actual definitions instead.

I actually like informal definitions a lot. I think they serve two different purposes:

1. For beginners they usually soften the blow of a fully rigorous definition, letting them get an idea of the concept before getting it exactly.

2. For experts they can often suggest what the exact definition is faster than it would be to read a precise definition!

But if you don't get anything out of them, you can skip 'em. Definitions are more important: informal descriptions are there to help you grasp the definition faster and to help you develop an intuition for the concept being defined. If you can do those things faster from just a rigorous definition, you don't need an informal description. (But as I said, I feel informal descriptions benefit both beginners and experts, so I'd also suggest practicing reading them more to get a feeling for what kind of details people tend to omit or emphasize.)

[cryptica]

It's not about 'informal definitions'. I also really like informal definitions but not the way that most mathematicians currently tend to write them.

[omaranto]

Wait, are you complaining about how mathematicians currently tend to write informal descriptions of concepts or about the informal descriptions in the intros to Wikipedia articles? I think those things are pretty different.