The Difference between нужно and надо

Did you know that нужно and надо, used with a verb, are synonyms? They both mean “it is necessary to do somehting”, and they are used with infinitives. However, надо is a more colloquial option than нужно. Надо cannot be used with a noun, нужен (нужно, нужна, нужны) can be used with nouns, depending on their gender and number.

For example,

Мне надо (нужно) пойти к врачу. I need to go to the doctor.
Мне нужно новое кресло. I need a new armchair.