In Angular, directives are a way to extend the functionality of HTML by defining custom HTML elements, attributes, or structural markers. Directives in Angular are of two types:

Component Directives: These are used to create reusable UI components in Angular. They are defined using the @Component decorator and consist of a template, styles, and a class.

Attribute Directives: These are used to change the behavior or appearance of an existing HTML element or component. They are defined using the @Directive decorator and can be used as attributes on HTML elements.

Directives in Angular can be further categorized as:

Structural Directives: These change the structure of the DOM by adding, removing, or manipulating elements. Examples include ngIf, ngFor, and ngSwitch.

Attribute Directives: These change the appearance or behavior of an element by adding, removing, or modifying an attribute. Examples include ngStyle, ngClass, and ngModel.

Directives in Angular are a powerful feature that allows developers to create reusable components and customize the behavior and appearance of existing HTML elements. They help in creating modular and maintainable code by separating concerns and promoting code reusability.