Final answer:
An adverb intensifies and adds information to the word it is modifying.
Step-by-step explanation:
An adverb intensifies and adds information to the word it is modifying. For example, in the sentence 'She runs quickly,' the adverb 'quickly' modifies the verb 'runs' by providing information about how she runs.
Adverbs can also modify adjectives and other adverbs. For instance, in the sentence 'He is extremely tall,' the adverb 'extremely' modifies the adjective 'tall.' Similarly, in the sentence 'She sings very loudly,' the adverb 'loudly' modifies the adverb 'very.'