CSS3 (~2009-2012):

Level 3 CSS specs as defined by the CSSWG. (immutable)

CSS4 (~2013-2018):

Essential features that were not part of CSS3 but are already a fundamental part of CSS.

CSS5 (~2019-2024):

Newer features whose adoption is steadily growing.

CSS6 (~2025+):

Early-stage features that are planned for future CSS.

“I’ve written before about how React is the new default frontend framework, and how I don’t think most people using React on a regular basis realize quite how much it’s fallen behind.” High level thoughts about the React ‘bubble’ and some reasons to look beyond it, including a round up of some of the alternative options. 

What's new in C#? - Exciting new features in C# 9, 10 and 11! - Filip Ekberg - NDC Oslo 2023

We will cover the following features:
- Nullable reference types
- Pattern Matching in C# 8 = C# 11
- Record types
- Top level programs/statements
- Init only & new()
 

When you think about C#, you'll usually think about a high-level language, one that is utilized to build websites, APIs, and desktop applications. However, from its inception, C# had the foundation to be used as a system language, with facilities that allow you direct memory access and fine-grained control over memory and execution.

ILogger: is responsible to write a log message of a given Log Level.

ILoggerProvider: is responsible to create an instance of ILogger (you are not supposed to use ILoggerProvider directly to create a logger)

ILoggerFactory: you can register one or more ILoggerProviders with the factory, which in turn uses all of them to create an instance of ILogger. ILoggerFactory holds a collection of ILoggerProviders. 

Here’s a summary of what’s new in this preview release:

• HTTP/2 performance improvements
• Typed results for minimal APIs
• OpenAPI improvements for minimal APIs
• Return multiple results types from minimal APIs
• Route groups
• Client results in SignalR
• gRPC JSON transcoding
• Project template option to use Program.Main method instead of top-level statements
• Rate limiting middleware 

C# 9 Cheat Sheet with code example and pros and cons.

• Records
• Init only setters
• Top-level statements
• Pattern matching enhancements
• Native sized integers
• Function pointers
• Suppress emitting localsinit flag
• Target-typed new expressions
• static anonymous functions
• Target-typed conditional expressions
• Covariant return types
• Extension GetEnumerator support for foreach loops
• Lambda discard parameters
• Attributes on local functions
• Module initializers
• New features for partial methods