Simple Serialize, or SSZ, is a serialization and deserialization protocol used extensively in Ethereum. From a .NET/C# developer's standpoint, think of SSZ as akin to serialization frameworks you might be familiar with, like JSON.NET or XML Serialization in .NET, but with specific optimizations and features tailored for blockchain technology.

.NET Core is an open-source, cross-platform framework developed by Microsoft for building modern applications. It enables the development of applications and services that run on Windows, Linux, ARM and macOS. As a modular and lightweight version of the .NET Framework, it's designed for high performance and supports multiple programming languages, including C#, F#, and Visual Basic. .NET Core's versatility and efficiency make it a popular choice for enterprise software development.