Cognitive friction is the mental effort a visitor has to spend to figure out what your page is, what it's offering, and what they're supposed to do next. The phrase comes from interaction design — every extra word, ambiguous label, surprise modal, or layout shift forces the visitor to think harder, and thinking harder is something most visitors won't do for long.
I test for it the same way every time: open a page in a new tab, read the first screen, and ask whether I could explain the page to someone in one sentence. If I can't, the page has a friction problem and the fix is almost always cutting, not adding.
The common sources are predictable. Headlines that lead with adjectives instead of nouns. Forms that ask for a phone number when an email would do. Navigation that uses internal jargon ("Solutions" / "Platform") instead of plain labels. Pop-ups that fire before the page has loaded. Layout shift while images and ads load in. Inline cookie banners that block the call-to-action on mobile. Each of these costs a small fraction of visitors, and they compound.
Reducing friction doesn't mean stripping a page bare. It means making sure the work the page is asking the visitor to do — read, scan, click, type — matches the energy they came with. A blog reader has more attention than a Google search visitor, who has more than a returning customer trying to find a phone number. The page that respects the difference converts better and ranks better, because dwell time and scroll depth are real signals to search engines about whether the page met intent.