Neural network
A neural network is a mathematical structure loosely inspired by the brain: layers of simple units pass numbers to each other through weighted connections. Training adjusts those weights so the network's outputs get closer to the right answers.
In one line, for a 12-year-old
A neural network is a huge web of dials that the computer keeps nudging until it gets the answers right.
An example
When a translation app turns "Bonjour" into "Hello", a neural network with billions of tuned connections does the work.
Why it matters to people
Calling these systems "brains" can make them sound more human than they are. They are powerful pattern-matchers, not minds, and that framing helps keep expectations and trust realistic.