What is dark matter, why is it named dark matter, and are there any other forms of matter?

Question: What is dark matter, why is it named dark matter, and are there any other forms of matter?
- Keywords:
  dark matter
Asked by anon-335301 on 5 Oct 2022. This question was also asked by anon-336762.
- Jack Reid answered on 5 Oct 2022:
  
  We are not exactly sure what dark matter is, which is why we call it ‘dark’, but it must be present and represent are large proportion of the mass in the Universe. Regular matter makes up the rest, with which we are familiar.

Question: What is dark matter, why is it named dark matter, and are there any other forms of matter?