Asp.Net core is a web development platform introduced by Microsoft.  

Asp.Net core consists of a platform for processing HTML requests, frameworks for creating applications, and a secondary utility framework that provide the supporting feature. 

Let's understand in details: 

1) Application framework: 

There is 3 application framework: 

1. MVC Framework: Model view controller pattern 

2. Razor pages:  Razor page contain Code and content mixed to form a self-contained page, it's part of MVC 

3. Blazor: is a new framework in .net core 

2) Utility Framework: 

There are 2 utility frameworks 

1. Identity 

2. Entity Framework 

3) Platform 

Forex. 

1. HTTP server 

2. Middleware 

3. URL Routing

4. Dependency Injection 

5. Configuration & Logging

6. Caching 

7. Model Binding 

8. Razor

9. gRPC

10. SignalR