Something I read a couple of weeks ago discussed this. From what I remember it’s to increase the time a user spends on a page, this increases the page ranking in Google; ISTR it was called dwell time.
Acronym expanded for the benefit of anyone else who's browsing HN before coffee and would have taken a similarly embarrassing length of time to infer the likely meaning of this one, which I'd never seen before.
I've always known is as "I Seem To Remember" and I thought it was in common use. It's been around for as long as I can remember, apologies for assuming.
