Step: Explicit counts: {n,m}

{n} matches exactly n times, {n,} n or more, and {n,m} between n and m times.

Why it matters: many real formats have fixed widths — a 4-digit year, a 2-digit month, a 3-to-4-digit code.

Example: \d{2,3} matches 2 or 3 digits at a time.

Your turn: match "22", "333", and the first three digits of "4444" with \d{2,3}.

Pitfall: {2,3} is greedy, so from "4444" it takes "444" first, leaving a lone "4" that is too short to match.