Modular software is a design approach that breaks down a program into smaller, independent components called modules. Each module can perform a specific function and can be developed, tested, and maintained separately. This structure allows for easier updates and modifications, as changes in one module do not necessarily affect others. By using modular software, developers can enhance collaboration and reuse existing code, leading to faster development times. Popular programming languages like Python and Java support modular programming, making it easier for teams to work together on complex projects while maintaining a clear organization of code.