Scripting
Scripting in Unity uses C# and is very well documented. In the sections below, I'll Provide examples and edge cases where possible, and link to the relative documentation for quick reference.
For a collection of classes and structs that are required for Unity to function, which means they will always be available to you when scripting in Unity, head over to UnityEngine.CoreModule Documentation
Transform
Official Transform Class Documentation
Vector3
Official Vector3 Struct Documentation