system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is the Queen of England's husband a Prince?

If Queen Elizabeth is married to Prince Philip why is he not King Philip? I am confused because when Prince William becomes King won't Kate become Queen Katherine? How is title decided? And what about Camilla when Charles becomes King, what will her title be?
gpt
There are two types of queen.

Queen Elizabeth is a Queen Regnant, meaning she is the queen by succession (ie. by birth).

A Queen Consort is the wife of the reigning king.

However, there is no equivalent for kings. The only way to be a king is by succession.

When William is King, Kate will be Queen Katherine, because she will be the Queen Consort. When Charles is King, Camilla will have the right to call herself "Queen". However, it's unlikely that she will do so. She will probably be known as Princess Consort Camilla. This is because the memory of Princess Diana is a sensitive subject, and she doesn't feel it would be the right thing to call herself Queen.