OptionalcharsetThis attribute declares the document's character encoding.
If the attribute is present, its value must be an ASCII case-insensitive match for the string "utf-8",
because UTF-8 is the only valid encoding for HTML5 documents.
<meta> elements which declare a character encoding must be located entirely within the first 1024 bytes
of the document.
OptionalcontentThis attribute contains the value for the http-equiv or name attribute, depending on which is used.
Optionalhttp-Defines a pragma directive. The attribute is named http-equiv(alent) because all the allowed values are names of particular HTTP headers.
OptionalidThe id global attribute defines a unique identifier (ID) which must be unique in the whole document.
OptionalmediaA valid media query list that can be included to set the media the theme-color metadata applies to.
OptionalnameThe name and content attributes can be used together to provide document metadata in terms of name-value pairs, with the name attribute giving the metadata name, and the content attribute giving the value.
OptionalpropertyThe property attribute is used to define a property associated with the content attribute.
Mainly used for og and twitter meta tags.
From T, pick a set of properties whose keys are in the union K