as an adverb (following ‘very’ and an adjective or another adverb): The results were very good indeed.
as a way of showing how a sentence or phrase is related to what has already been said: It would be difficult. Indeed it would be almost impossible.
as a sentence adverb (with an auxiliary verb or the verb ‘to be’, to emphasize the meaning of a whole sentence or clause): It is indeed an honour to have such an important guest with us today. ♦ ‘Mr Benson wants to make a complaint.’ ‘Does he, indeed?’