Sliding-window attention
Also: local attention
Restricting each position to attend only to the last w tokens instead of the whole prefix, making cost linear in sequence length rather than quadratic.
What people get wrong
Information still travels further than the window: each layer moves it another w positions, so a deep stack has an effective reach of layers times window.
A definition is not an understanding. This is taught properly in What modern models actually do differently, part of Transformers & attention.
Learn this properly