Adverbials

Adverbials are words or phrases that give more information to the sentence.

"I discovered fronted adverbials earlier today."

'Earlier today' is the adverbial.

Fronted adverbials

A fronted adverbial is when the adverbial word or phrase is moved to the front of the sentence, before the verb.

"Earlier today, I discovered fronted adverbials."

So here, 'earlier today' is a fronted adverbial.