Input Validation is the process of ensuring that the data provided by users meets specific criteria before it is processed by a system. This helps prevent errors and ensures that the data is in the correct format, such as checking if an email address contains the "@" symbol or if a number falls within a certain range. By implementing Input Validation, developers can protect their applications from malicious attacks, such as SQL Injection or Cross-Site Scripting (XSS). Proper validation enhances security and improves the overall user experience by providing immediate feedback when incorrect data is entered.