To serve the ones among you interested in the linguistic theory we will have a short excursion into the differences between conjunctions, adverbs and pronouns. The reason for this is that quite often an adverb or a pronoun is used as conjunction, even though the original function of adverbs and pronouns are different.
Basicly adverbs, pronouns and conjunctions are different things (otherwise they would not have different names!).
The adverb describes features of a verb, an adjektive or another adverb.
He runs quickly.
This is very nice.
She runs tremendously quickly.
The pronoun substitutes something that can be adjectival or substantival.
This is my house.
It is mine.
He crosses the street.
I see him.
A conjunction creates a connection between clauses and elements of a clause.
I like him, because he is beautiful.
The dog is fun and always kind.
His dog as well as mine run through the park.
Then we find cases where words are cataloguized as adverb, but they have the function of a conjunction. For instance pronominal adverbs take this special function and make things sometimes a bit difficult.
He wants to buy a car, therefore he saves money.
He wants to buy a car, although he still has not enough money saved.
He looks into the sky, hereby he cannot see the accident.
He looks into the sky and cannot see the accident.
therefore, thereof, hereby, wherein, whereof etc.
However, to understand and learn the language this knowledge is not essential. We just explained this, because we would have asked this ourselves.