What is the difference between GBK GB2312 GB18030 in the character encoding of a computer

GBK and GB2312 are all 16-bit,

GBK supports Simplified Chinese and Traditional Chinese, while GB2312 only supports Simplified Chinese, GBK contains GB2312, with more GBK

GB18030 is 32-bit, it supports Simplified Chinese, Traditional Chinese Tibetan, Mongolian, Uyghur and other major minority characters,

Includes GBK and GB2312

That is to say, from GB2312 (1980), GBK (1995) to GB18030 (2000), these coding methods are backwards compatible

What is the difference between GBK GB2312 GB18030 in the character encoding of a computer