What does htr mean in crochet?

British notation

“htr” only exists in British notation. A US pattern writes “hdc” for this stitch.

Try it with a row from your pattern

Here is a row that uses it. Replace it with a row from your pattern: every abbreviation the reader knows is underlined, and its meaning shows on hover.

Row 2: ch 2, htr in each st across, turn (18)