Design patterns in TypeScript, as in any programming language, are reusable and proven solutions to common problems that developers encounter during software development.

These patterns provide a blueprint for structuring code in a way that promotes maintainability, scalability, and readability. They help in solving specific design challenges while adhering to principles like the Single Responsibility Principle, Open-Closed Principle, and more.

TypeScript, with its strong typing and object-oriented features, is particularly well-suited for implementing various design patterns.

Here are some key design patterns in TypeScript:

Creational Patterns:

1. Singleton Pattern: Ensures that a class has only one instance and provides a global point of access to it.

2. Factory Pattern: Defines an interface for creating an object but lets subclasses alter the type of objects that will be created.

3. Abstract Factory Pattern: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.

4. Builder Pattern: Separates the construction of a complex object from its representation, allowing the same construction process to create different representations.

5. Prototype Pattern: Creates new objects by copying an existing object, known as a prototype.

Structural Patterns:

1. Adapter Pattern: Allows the interface of an existing class to be used as another interface.

2. Decorator Pattern: Attaches additional responsibilities to an object dynamically.

3. Facade Pattern: Provides a unified interface to a set of interfaces in a subsystem.

4. Bridge Pattern: Separates an object's abstraction from its implementation, allowing both to vary independently.

5. Composite Pattern: Composes objects into tree structures to represent part-whole hierarchies.

Behavioral Patterns:

1. Observer Pattern: Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

2. Strategy Pattern: Defines a family of algorithms, encapsulates each one, and makes them interchangeable.

3. Command Pattern: Encapsulates a request as an object, thereby allowing for parameterization of clients with queues, requests, and operations.

4. State Pattern: Allows an object to alter its behavior when its internal state changes.

5. Chain of Responsibility Pattern: Passes a request along a chain of handlers, allowing each handler to decide to process the request or pass it to the next handler in the chain.

Architectural Patterns:

1. MVC (Model-View-Controller) Pattern: Separates an application into three interconnected components: the Model (data and business logic), the View (presentation and user interface), and the Controller (user input processing).

2. MVVM (Model-View-ViewModel) Pattern: Enhances the separation of concerns by introducing a ViewModel that acts as an intermediary between the View and Model.

3. Dependency Injection: Inversion of Control (IoC) pattern that helps manage dependencies and their lifecycle.

Concurrency Patterns:

1. Promise Pattern: Represents a value that may not be available yet but will be at some point in the future, allowing asynchronous code to be more manageable.

2. Async/Await Pattern: Provides a syntax for writing asynchronous code in a more synchronous style, improving readability and maintainability.

Design patterns promote code reusability, maintainability, and modularity. They help developers communicate and share solutions to common problems. When applying design patterns in TypeScript, you can take full advantage of TypeScript's strong typing to create more reliable and maintainable code. It's essential to choose the right pattern for the specific problem you're trying to solve and to understand when and where to apply these patterns effectively.