Definition - As the name suggests, conjunctions are words that join other words, clauses, or sentences:
             • und [and], oder [or], sondern [but], sowie [as well as], weil [because], ...

Types - There are many types of conjunctions that indicate different kinds of connection: inclusion, alternative, exclusion, contrast, time, manner, cause, effect, purpose, condition, doubt, etc. Sometimes pairs of conjunctions are used together to connect different words or groups of words within the sentence.
Coordinating conjunctions link clauses of the same kind, for instance main clauses that express ideas with the same importance in the overall meaning of the sentence.
Subordinating conjunction introduce subordinate clauses, which are clauses that depend on the rest of the sentence to make complete sense.

Examples of German conjunctions:
             • Das kleine Flugzeug kommt von London und fliegt nach Frankfurt.
                [The small plane comes from London and flies to Frankfurt.]
             • Das Restaurant ist sehr gut, aber es ist teuer.
                [This restaurant is good, but it is expensive.]
             • Ist es ein Uhr oder zwei Uhr?
                [Is it one or two o'clock?]
             • Das ist weder ein gelber Koffer noch eine rote Tasche, sondern eine braune Brieftasche.
                [This is neither a yellow suitcase nor a red bag, but a brown wallet.]