adverb
Describes doing things sequentially, each in its proper turn, often with a sense of methodical progression.
順々に名前を呼ばれた。
Our names were called one by one.
問題を順々に解決していきましょう。
Let's solve the problems one after another.
次々に means 'one after another' in rapid succession, without the sense of a predetermined order that 順々に carries.
Reduplication of 順 (order, turn) with the adverbial particle に, emphasizing a sequential, step-by-step manner.