Are headings automatically bold?

Question

<h1> <h2> <h3> <h4> etc. are automatically bold? An answer with an explanation would be appreciated, thanks!

Answer 1

Yes. All heading are by default Bold and increased sized.
You can alter these with the help of CSS.
Its because, headings are something which briefly describes something under it. So a person can get to know what content will be inside a particular heading.
So, they are bold to standout from rest of the content, to separate different contents, to catch reader's eyes about something special.
You know What I mean