what makes a language
Many of you may be thinking "well what makes a language a language?" This is a great question. When we take a look at English, we notice that there are differences between the different kinds of English that are spoken. The English spoken in the United States (American English) is different from the English spoken in the United Kingdom (British English) and even that is different from Australian English. But what makes all of these different varieties of English, English?
American English, British English, and Australian English are all dialects of English. Those who speak a dialect of English are all bound together by a social identity. Dialects have their own language rules that may be different from the "Standard" of that language.
How then do we know when something becomes a language? Years from now, British English and American English may diverge so much that they are no longer mutually intelligible. There's a saying that goes around that says "a language is a dialect with an army and a navy." This means that languages are often reinforced by politics, governments, and power structures.
The stages in between a language becoming officially a language are called pidgins and creoles. Pidgins occur when there is a mixing between a primary language and elements from another language. A creole is when a stable natural language has developed from this mixture of languages. One of the most famous creoles that exist is Haitian Creole, which is a blend of French with influences from Portuguese, Spanish, English, Taíno, and West African languages. It is spoken by the majority of people in Haiti.
Languages themselves then contain all of the fields of linguistics that are covered in the Fields of Linguistics page including morphology (words), phonology (sounds), syntax (sentence structure), semantics (meaning), and have evolved over time (historical linguistics). Many languages are written and spoken, but not all languages are written. Written languages contain alphabets to write with, which you can read more about on the Linguistic Tools page.
Beyond all of these facets of language comes your own personal idiolect. This contains your own personal mental lexicon, which is a collection of vocabulary words with your own personal definitions. If you ask a group of people what a certain word means, chances are that while a lot of the answers will be similar (or even the same), chances are that they will all vary slightly (perhaps even more than slightly). This is because we each have our own unique experiences with using language. While Standardized grammar and vocabulary may seek to regulate these things, everyone will still have their own personal relationship with using language.