Should I declare charset like this:
<meta http-equiv="content-type" content="text/html" charset="UTF-8">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
Updated in light of @Alohci's comment.
encoding declaration state (
The encoding declaration state is just an alternative form of setting the
charsetattribute: it is a character encoding declaration. This state's user agent requirements are all handled by the parsing section of the specification.
For meta elements with an
http-equivattribute in the Encoding declaration state, the content attribute must have a value that is an ASCII case-insensitive match for a string that consists of: the literal string
"text/html;", optionally followed by any number of space characters, followed by the literal string
"charset=", followed by one of the labels of the character encoding of the character encoding declaration.
A document must not contain both a meta element with an
http-equivattribute in the encoding declaration state and a meta element with the
charsetattribute present. (emphasis mine)
Therefore, if you are going to use
http-equiv, it must be used as
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">. But, that's just another way of saying
<meta charset="utf-8">, so use the abbreviated form.