Language is systematic or rule governed. Although this is true, it is also true that there is often variation in the actual use of any language. All users of the same language do not necessarily use it in the same way. Often the same speaker may use the same language in different ways depending on a number of factors.
A dialect is a variant of a language. If it is associated with a geographically isolated speech community, it is referred to as a regional dialect. However, if it is spoken by a speech community that is merely socially isolated, it is called a social dialect. These latter dialects are mostly based on class, ethnicity, gender, age, and particular social situations. Black English (or Ebonics) in the United States is an example of a social dialect.
Code switching: People may quickly switch back and forth between dialects, depending on the person they are talking to at the time. This pattern is referred to as diglossia or "code switching." Code-switching is a term in linguistics referring to alternation between two or more languages, dialects, or language registers in the course of discourse between people who have more than one language in common. Sometimes the switch lasts only for a few sentences, or even for a single phrase.
More broadly defined, code-switching occurs when people alter their speech and behavior so as to fit into different social situations. The most common changes involve vocabulary, levels of casualness or formality, types of clothing, and facial and hand gestures.
Dis ting called language is real funny
We does use it for all kinda ting you see
Sometimes it fancy and sometimes it free
And in did Caribbean is a real potpourri
When it fancy we it formal and real ‘la de da’
When it free we does call it vernacular
Each country down here have it own language flavour
But they each have a standard that they must master.