Custom Validators

Custom validators in Angular are functions that allow you to define your own validation logic for form controls. They are used when the built-in validators (like required, minLength, etc.) do not meet your specific validation requirements. A custom validator is a function that returns either null if the form control is valid, or an object that represents the validation error if it is invalid. This object typically contains a key-value pair where the key is the error name and the value is a boolean or some details about the error.