Dialectology is a study of language that focuses on understanding dialects. It is part of a larger group of studies called sociolinguistics, which evaluates the many elements that shape communication in whole cultures or in smaller groups. When dialectologists study language they are principally concerned with identifying how the same language can vary, based on a number of circumstances. This does not simply mean pronunciation changes, but can also mean differences in word choice, spelling and other factors.
It can be a little difficult to determine what constitutes a dialect. Dialectology may define this as meeting several flexible standards. These include that the dialect can be well understood by speakers of the language who don’t use it, and that those using the dialect can understand the common language used by others. A good example of this might be someone who speaks in an American dialect but can understand a British television show; this is called mutual intelligibility.
Those interested in dialectology also take into account how speakers of the dialect would perceive their own language, and if they view it as part of a larger language or as separate from it. Additionally, dialect or language may sometimes be defined politically, even if it bears similarity to another language. Leaders of countries, for instance, could declare that two languages are separate, for a variety of reasons.
Once a person working in dialectology determines that the use of language in a particular area or social group constitutes a dialect of a main language, study of the development of that dialect can prove helpful. Since languages frequently have multiple dialects, this can say much about the development of a society over time. For instance a flood of immigration to a particular area might change word choice, pronunciation and usage, and the development of a separate dialect may be studied to evaluate if it corresponds with mass immigration. In a sense dialectology becomes the linguistic analysis of political and social history, in addition to specifically describing changes between one dialect and another.
While dialectology may principally focus on studies of dialect as a revealing aspect of history, society and language development, this work is significant in the present. In any country or area where there are multiple dialects, like the US or UK, some knowledge of dialectology may be useful in teaching, especially when instructing early readers and writers. Understanding that words read aloud might be pronounced differently may help teachers grade accordingly. Similarly if dialect differences are significant, students may write using word choices that appear non-standard. Should these students need to write a more homogeneous form of English, they might need extra help, instruction, and support in the classroom.