How do transformers increase voltage, and how much can they increase it?

I need help understanding how voltage gets increased by transformers.How do transformers increase voltage, and how much can they increase it?http://en.wikipedia.org/wiki/TransformerHow do transformers increase voltage, and how much can they increase it?
A transformer "changes" voltage and current for only for alternating

current (AC). You can think of a transformer as two coupled

electromagnets. When you pass the current through the "input" side, you

generate a magnetic field. If this field "crosses" another conductor (in

the case of the transformmer, the "output" side), voltage and current are

induced this conductor as a function of the "rate of change" of the

magnetic field. The amount of voltage and current is a function of

the "turns ratio" of the transformer, that is the ratio of the turns on

the input coil to the output coil. If the number of turns are equal, then

the induced voltage and current are equal to that on the input side. If

the output side has twice as many turns, the output current is half of the

input current but the output voltage is double the input. (In reality it

will be a bit less due to losses.)How do transformers increase voltage, and how much can they increase it?inside transformers theres a oil in thousands of coils that the energy runs through and somehow multipies and increases the voltage and it can also down grade itHow do transformers increase voltage, and how much can they increase it?
steps up, steps down, chokes it, pretty much morphs it. the transformers on the street take power from 33,000 VAC and step it down to 120 VAC for your homeHow do transformers increase voltage, and how much can they increase it?what megan said+transformers are for both AC and DC