Chunking is a method of presenting information which splits concepts into small pieces or "chunks" of information to make reading and understanding faster and easier. Chunking is especially useful for material presented on the web because readers tend to scan for specific information on a web page rather than read the page sequentially.

Chunking (writing)
How Chunking Helps Content Processing
Nielsen Norman Group
How to Chunk Content into Scannable Pages
UX Movement
Interaction Design Foundation
User Interface Design, Getting the Basics Right
UX Booth