Bayrisch (Bavarian) Dialect
Bayrisch (also Boarisch or Bairisch) is widely considered a dialect of German, although Old Bayrisch actually predates Old German by a few centuries. Spoken widely throughout Bayern (Bavaria) as well as Austria, there are approximately 14 million speakers worldwide. Although written Bayrisch is decreasingly used, as Hochdeutsch or Schriftdeutsch (Written German) is taught in schools, written Bayrisch survives in the form of slang or texting. Bayrisch speakers can understand Hochdeutsch, but the relationship is not mutual. Here are some resources for learning about the dialect, as well as a few guides to the language itself.
Standard German vs. Bayrisch: A funny video comparing the sounds of the two languages.
Dialects of German: A video comparing twelve different dialects of German.
Boarische Wikipedia: Read Wikipedia articles written in Bayrisch.
Why learn Bavarian?: A blog post about why you might want to learn Bayrisch.
Bayrisch Lernen: A grammar, pronunciation, and vocabulary guide, written in German and Bayrisch.
Bayriches Wörterbuch: A Bayrisch – German dictionary and pronunciation guide, searchable by letter.
Deutsch – Bayrisch Translator: An online translator from Hochdeutsch into Bayrisch. Unfortunately, it is not reversible.