Why this matters: a lot of great crochet magazines and patterns — Simply Crochet among them — are written in UK terms. UK and US crochet use the same stitches but swap the names almost entirely, so following a UK pattern with US terms in your head will not turn out right.

Stitches

These are exact, 1-for-1 swaps — same stitch, different name.

UK termUS term
Double crochet (dc) → Single crochet (sc)
Half treble crochet (htr) → Half double crochet (hdc)
Treble crochet (tr) → Double crochet (dc)
Double treble crochet (dtr) → Treble crochet (tr)
Triple treble crochet (trtr) → Double treble crochet (dtr)
Slip stitch (ss) → Slip stitch (sl st) same stitch
Chain (ch) → Chain (ch) same stitch

Other pattern words

Not stitches, but common enough to trip you up mid-row.

UK termUS term
Miss→Skip
Tension→Gauge
Yarn over hook (yoh) → Yarn over (yo)