What is cognitive load and why does it matter in copywriting?

Cognitive load is the mental effort required to process information. High cognitive load-complex sentences, too many choices, dense text-exhausts readers. They disengage, skim past important content, or abandon the email entirely.

Reducing cognitive load: Simple sentences (one idea each). Clear hierarchy (what's most important?). Chunked content (paragraphs of 2-3 sentences max). Limited choices (one primary CTA). Familiar words (avoid jargon unless your audience expects it). White space (visual breathing room).

Make it easy to say yes. Every moment of confusion is friction toward your goal. If readers have to re-read a sentence, you've lost momentum. If they can't figure out what to click, they won't click anything. The best email copy feels effortless to consume-which requires significant effort to write. Simple is hard.