There are two meta tags that seem very similar: description and abstract. What is the difference between the two?
What is the difference between the description and abstract meta tags?
seo;meta tags;meta description
It depends on the definition of abstract.For HTML5, abstract is not registered. So you must not use this metadata name in (X)HTML5 documents. The metadata name description is defined in the HTML5 specification itself, so its valid to use it in (X)HTML5 documents.In HTML 4.01, you can use any metadata names, so using abstract would be allowed. But it should be defined in a profile:This specification does not define a set of legal meta data properties. The meaning of a property and the set of legal values for that property should be defined in a reference lexicon called a profile.Metadata can only be useful if its use/scope is defined (e.g. in specifications) resp. documented (e.g. by metadata consumers).