What is the difference between Go's built-in error type and custom error types in Go programs?

In Go, the built-in error type is an interface that has a single method called Error() string. This means that any type that implements the Error() method can be used as an error type.

Custom error types in Go programs are simply user-defined types that implement the **error** interface. By creating custom error types, developers can provide additional context and information about the error, making it easier to debug and understand error conditions.

Using custom error types can also help with type safety and prevent errors from being accidentally masked or ignored. Additionally, custom error types can be defined with their own fields and methods, allowing for more sophisticated error handling logic.

In summary, while the built-in **error** type can be used in Go programs for basic error handling, custom error types can provide additional context and functionality for handling more complex error conditions.