Good morning!  Have you ever heard someone speak with a thick accent and wondered where accents come from?  It turns out there is an entire field of study focused on accents.
I have heard of people speak with accents, but had no idea it was an area of study!
Yes, it's called sociolinguistics.  Accents appear even within languages so there are numerous accents within the English language across regions. 
DO they know what causes these different accents?
Yes!  From what I understand, these different accents result from variations in local dialects, and differences in standard English in different primary-speaking populations.  
That is fascinating!  So in other words, every language has differing accents within that language?
of their mother tongue in English speech. For more details, see Non-native pronunciations of English.
Primary English-speakers show great variability in terms of regional accents. Some, such as Pennsylvania Dutch English, are easily identified by key characteristics; others are more obscure or easily confused. Broad regions can possess sub-forms as identified below; for instance, towns located less than from the city of Manchester, such as Bolton, Rochdale, Oldham and Salford, each have distinct accents, all of which together
analysed by Johnson's team both for content and for where it was reported. "Perhaps the most remarkable finding in the Voices study is that the English language is as diverse as ever, despite our increased mobility and constant exposure to other accents and dialects through TV and radio". When discussing the award of the grant in 2007, Leeds University stated:
Dialects Regional.
Most people in Britain speak with a regional accent or dialect. However, about 2% of Britons speak with an accent called Received Pronunciation (also