Definition
Abstraction is the deliberate act of stripping away detail so that an underlying pattern becomes visible and usable. By ignoring what is irrelevant to the question at hand, an abstraction makes a complex thing tractable.
It is how thinking becomes possible at all. A map, a formula, a category, a model — each is an abstraction that trades completeness for usability. The skill lies in choosing which details to discard, because what is noise for one purpose may be the crucial signal for another.
Why it matters
How it works
You form an abstraction by asking which features are essential to your question and which can be ignored. The result is a simpler representation you can manipulate and share. The risk is forgetting what was left out: an abstraction built for one purpose can quietly fail when stretched to another.
Used well, abstraction lets a principle learned in one field illuminate a structurally similar problem in a completely different one.