What is Dofollow link?
Short answer
A link that passes ranking signals to its destination, as opposed to a nofollow or sponsored link, which tells search engines not to.
A link is dofollow by default. Adding rel="nofollow", rel="sponsored" or rel="ugc" tells a search engine to discount it.
Most large publishers mark paid placements as sponsored or nofollow, which is both their policy and Google’s stated requirement. Outlets that do pass a dofollow link on paid content charge more for it, and that premium is the honest reason for the price gap.
Why it matters
If you are buying placement for SEO rather than credibility, the link type is the single most important field on the page — and the one most price lists leave out.