Regular expressions, or regex, are text strings that allow developers to create patterns for matching, managing, and locating text, which can significantly enhance efficiency when working with large datasets. Despite variations across programming languages, regex provides common functionalities through shorthand character classes, quantifiers, character ranges, anchors, escape characters, flags, and specific string matching. These tools allow for precise text manipulation and pattern recognition, making them invaluable in software development. The text briefly covers various regex techniques like groups, look-ahead, and look-behind, while also acknowledging that more advanced applications exist beyond the scope of the discussion. Additionally, resources such as cheat sheets and guides are suggested for further exploration of regex capabilities.