An example of the use of later as an interjection is in the sentence, "I'm leaving now! Later!" which means, "I'm leaving now! Goodbye!"
An example of the use of later as an adverb is in the sentence, "We will go later," which means we will go at a future time.
She arrived on the ferry, and he came later. He later felt that he was wrong. Later on, we watched a movie.
My roommate arrived first. I arrived later.
I arrived later than my roommate.
I wanted to do it now, but I'll have to do it later.
The Victorian era is a later period of English history than the Elizabethan era.
The meeting was adjourned to a later date.