.NET Regex Tutorial
Not nearly as confusing as it is in JavaScript.
using System.Text.RegularExpressions;
bool mach = Regex.IsMatch("input", @"\w+", RegexOptions.None);
Match match = Regex.Match("input", @"\w+");
IReadOnlyList<Match> matches = Regex.Matches("input", @"\w+");
string result = Regex.Replace("input", @"(\w+)", "$1");