The original meaning of pore has nothing to do with skin; to pore means to examine carefully.

This lesser-known verb meaning of pore is usually followed by over or sometimes through. When you pore over a document, for example, you look at it very intensely. And before a big history test, you'll probably want to pore over your textbook.

The writers of these examples must've pored over their grammar notes because they nailed it:

In the meantime, forecasters with the National Hurricane Center are continuing to pore over data from last year in an effort to quality-control the season. (Washington Post)

We pored over that list, time and time again, going through it several times a day for several weeks. (Seattle Times)

Pour over sounds the same as pour over, which is why these two phrases are often confused. But when you pour, you cause a liquid to flow from a container — you don't look at something closely. At a coffee shop, you can order a pour over, when hot water is poured over the coffee grounds. In fact, you can pour liquid over anything you want, but that's not the same as studying or examining something — just ask anyone who's spilled coffee on their notes!

Perhaps the writers of the examples below imagine people pouring information like liquid, but their usage is incorrect. They should've used pored over:

Researchers poured over the data from several years and a few thousand crashes and found a 15% difference. (Washington Times)

I studied bylines just as much as I poured over the feature stories. (Salon)

It's a common mistake, but if you pore over the different meanings, you'll get it right every time. Remember that you pour water, but you pore over something that you need to focus on intensely.