Is there a way to provide summary on custom classes, methods etc. ?

When you type GameObject or any standard class, method etc. There is summary below.
Example: Screenshot by Lightshot
Is there a way to provide custom ones with this kind of summary?

Write this before your classes, methods etc.

/// <summary>
/// Write your summary here
/// </summary>
public var Name()

for more info go to: Recommended XML documentation tags for a class and its members | Microsoft Learn