Purport

After an honest request from Arjuna and knowing that Arjuna’s queries are valid and pure, Bhagvan Shri Krishna agreed to reveal his manifestations. Though Shri Krishna made it clear at this Shloka and also at the end of this chapter that there is no end of His (Shri Krishna’s) manifestations, neither of his potency, but he reveals some of the forms which are comprehended by human being easily.

Starting from this Shlokas until the end of the chapters, Shri Krishna explained some of his manifestation which happened in the past and which exist on earth at any given time. It is to be noted that there are varieties of manifestations mentioned, some of them are worthy of worship, some not. The purpose of revealing manifestations is not only for the purpose of worship but to reveal the expansion of potency of Bhagvan Shri Krishna.