Зачем и Почему. The difference?

Question

What's the difference between зачем? and почему?

Answer 1

Почему - why (we are interested in a reason)

Зачем - what for (we are interested in a goal)

Answer 2

Those a largely synonyms. Зачем means for what purpose and cannot be used where no purpose intended, like, Почему ты плачешь?

Answer 3

Почему - why (looking for a reson)

Зачем - what for (looking for a result)

Answer 4

The difference between зачем and почему is a matter of degrees. The former generally used as "for what purpose" whereas the latter is a broader "why?" Hope this helps!