Here's why:
* Adverbs modify verbs, adjectives, or other adverbs. They describe how, when, where, or to what extent something happens.
* The -ly suffix is a common way to form adverbs from adjectives. For example:
* Quick (adjective) becomes quickly (adverb)
* Happy (adjective) becomes happily (adverb)
However, not all adverbs end in -ly. Some adverbs are simply single words:
* Now, then, here, there, very, quite, always, never
And some adverbs are formed from adjectives without adding -ly:
* Fast, slow, well, hard, much, little
So, while -ly is a common ending for adverbs, it's not a foolproof rule.