Abstraction People naturally tend to clump multiple things into single things. Abstraction is about isolating a chain of events into a single event that's meaningful as a whole to the human mind. Computers can help with this. The more I can accomplish with a single command, and the further back I can stand from the nitty-gritty, and the more I can make my own actions be general and let the computer take care of the details, the better. It occurs any time you just don't want to be bothered with the details, especially when you think the details are stupid.
Abstraction piles on top of abstraction.
In the list of links example, isolating the task is an abstraction. Scripting UserTalk is a programming language that lets you calculate, repeat, and abstract. But it's also a scripting language, by which I mean that what it operates upon is your computer itself. It can read and write files directly. UserTalk is a programming language that has your whole computer as its scripting domain.