Crochet in the roundis mostly used to crochet round or squared pieces. The starting circle is made out of a chain, closed by a slip stitsh in the first stitch of the chain. The patterns is written in rounds instead of rows.
Each round starts with 1 or more chains. These chains allow to make room for higer stitches and stand for 1 of the repeated stitches of the row.
Increases are evenly spaced on each round. They are en important part in the shaping of the pattern.
You may find crochet in the round written patterns , but also diagrams.