Custom exceptions are a way to handle specific errors that can occur in a program, tailored to the needs of that particular application. They allow developers to create their own error types that can convey more precise information about the nature of the problem, rather than relying on standard error messages.

When you define a custom exception, you typically create a new class that inherits from a base exception class, like Exception in many programming languages. This new class can then be used to signal specific conditions that the program should handle differently from general errors.

For instance, if you’re developing a banking application, you might create custom exceptions such as InsufficientFundsException or AccountNotFoundException to handle scenarios unique to that application. By catching these specific exceptions, you can provide more meaningful error messages or take appropriate actions based on the type of error that occurred.

Custom exceptions enhance code readability and maintainability by making the error handling process more explicit and tailored to the specific needs of the application. They help in creating a clearer and more organized error-handling strategy, which ultimately leads to more robust and reliable software.