1: Presentation Tier This tier is often built on web technologies such as HTML5, JavaScript, CSS, or through other popular web development frameworks 2: Application Tier- The application tier contains the functional business logic which drives an application’s core capabilities. It’s often written in Java, .NET, C#, Python, C++, etc 3: Data Tier- The data tier comprises of the database/data storage system and data access layer. Examples of such systems are MySQL, Oracle, PostgreSQL, Microsoft SQL Server, MongoDB, etc. Data is accessed by the application layer via API calls