What does a hammer on mean in guitar tabs?

In guitar tablature, "hammer on" is a technique where you play a note without picking the string. Instead, you use the inertia of the fretting hand to hammer down on the string to create a note. It's notated as "H" or "HO". Here's an example:

- "5h7" means to hammer on the 7th fret while keeping the 5th fret held down.

Hammer-ons can be used to create smooth, connected melodies and add a percussive element to your guitar playing.