Software maintainability refers to how easily a software system can be modified to correct defects, improve performance, or adapt to a changed environment. High maintainability means that developers can quickly understand and update the code, which reduces the time and cost associated with making changes. Factors influencing maintainability include code readability, modularity, and documentation quality. Well-structured code that follows best practices allows for easier updates and troubleshooting. Tools and methodologies, such as Agile development and version control systems, also play a significant role in enhancing maintainability by facilitating collaboration and tracking changes effectively.