Anchor text
Anchor text is the visible, clickable words of a link, and it tells both users and search engines what the linked page is about.
When you create a link, the highlighted text is the anchor text. Search engines use it as a strong relevance signal: a link with the anchor project management software tells Google the destination is probably about that topic. This is why anchor text is one of the most influential, and most scrutinized, parts of any backlink profile.
Anchors fall into recognizable types: exact match anchor (the precise target keyword), partial match anchor, branded anchor (your brand name), naked url anchor (the raw URL), and generic anchor ("click here", "read more"). A natural backlink profile is dominated by branded and generic anchors, with only a small share of keyword-rich ones.
The biggest risk is over-using commercial exact-match anchors on inbound links. A spike of identical keyword anchors is a textbook over optimization footprint that Google's google penguin algorithm targets, and it can lead to a ranking drop or manual action. Aim for variety, and let your brand name carry most of your anchors.