The grep command is a powerful text search utility used in Unix and Unix-like operating systems. It allows users to search for specific patterns within files or input streams, making it invaluable for programmers and system administrators alike. By using regular expressions, grep can match complex patterns, enabling users to filter and analyze large amounts of text efficiently. Its versatility and speed make it a staple in scripting and data processing tasks, helping users quickly locate relevant information in logs, code, and other text files.