Regular Expressions (Regex) are sequences of characters defining search patterns. They are incredibly useful for searching, replacing, validating emails, or cleaning text data.
1. Character Classes
Use square brackets to match select characters: [a-z] matches any lowercase letter, while \d matches any digit (0-9).
2. Quantifiers
Quantifiers specify occurrences: * matches zero or more, + matches one or more, and {3} matches exactly three occurrences.
3. Anchors
Use ^ to match the start of a line and $ to match the end of a line, ensuring full string matches.