What are the meanings of common crochet pattern abbreviations?

Common crochet pattern abbreviations include:

• ch: chain
• sc: single crochet
• dc: double crochet
• hdc: half double crochet
• tr: treble crochet
• sl st: slip stitch
• inc: increase
• dec: decrease

These abbreviations are used in crochet patterns to indicate specific stitches and techniques.