In spite of - used to express the idea of contrast.
A). In spite of - is used as a preposition. In spite of + noun means almost same as although + clause.
e.g - We went out in spite of the rain. ( = .... although it was raining.)
B). In spite of is the opposite of because of .
e.g - She passed her exams in spite of her teacher. => (She had a bad teacher)
She passed her exams because of her teacher. => (She had a good teacher).
C). In spite of cannot be followed directly by a that - clause. Instead we can use in spite of the fact that
e.g - He is a good company in spite of the fact that he talks all the time.
Note - In formal English, despite can be used in the same way as in spite of.
Sita went on working in spite of feeling unwell.-- Correct
Sita went on working despite feeling unwell.-- Correct