Here's why:
* Mutual intelligibility: While there are regional variations (dialects), speakers of English from different parts of the world can generally understand each other. This is a key characteristic of a language.
* Standardized form: English has a standardized written form (spelling, grammar) and a widely accepted pronunciation standard (though there are many regional variations).
* Independent language: English has its own history, vocabulary, and grammatical structures, not derived from another language.
Dialects are variations within a language. For example, American English, British English, and Australian English are all dialects of the English language. They share a common core but have differences in pronunciation, vocabulary, and grammar.
So, while English has many dialects, it is a distinct language in its own right.