A "try-catch block" is a programming structure used to handle errors or exceptions that may occur during the execution of code. The "try" section contains the code that might cause an error, while the "catch" section defines how to respond if an error occurs. This helps prevent the program from crashing and allows developers to manage errors gracefully. Using try-catch blocks improves code reliability and user experience. When an error is caught, developers can log the issue, display a user-friendly message, or take corrective actions. This structured approach makes it easier to maintain and debug code, ensuring smoother operation of applications.