Questions Answered by Adverbs
When we first learn about Adverbs from Schoolhouse Rock, we are blithely told that they are formed from adjectives and conveniently end in -LY. This standardized approach to English, in this case, forming adverbs from adjectives, I've read, took hold in the 1700s. Examples are "happily, courageously, blithely, conveniently." The basic formula is that we simply add -LY to an adjective: happy + LY = happily, courage + LY = courageously, convenient + LY = conveniently, etc. That's true enough and it probably covers most of the adverbs out there.
However...and NOTHING against Schoolhouse Rock!... this easy, "Adverbs 101" approach leaves a lot of important and frequently used adverbs out in the cold (see the second chart below), which is sad. Even worse, it can be downright misleading, maybe even, shall we say, downrightly dangerous... Whoops, case in point: "downright" (a "to what degree" adverb) is already an adverb; no need to add LY. ("Downrightly," sorry to say, is not even a word.)
So looking for -LY endings is not the magic bullet. You see, there are also a number of words ending in LY that are not adverbs. These include adjectives formed by adding LY to nouns, such as love + LY = lovely, or mother + LY = motherly, as in "lovely day," or "motherly concern." So this is a friendly reminder (what kind of reminder?) that if we just scan the page, on the prowl for words ending in -LY, we will be quite misinformed. (Hmm, can you find the two adverbs in the previous sentence?) It turns out that the practice of adding -LY to nouns to form adjectives was something from Middle English, and when this came to an end, it "paved the way" for adverbs to take over the -LY ending.
As you will soon see, knowing the questions that adverbs answer is the best way to learn to identify adverbs. These five questions are HOW, WHEN, WHERE, TO WHAT DEGREE, and WHY. This approach works wonders and will get you thinking grammatically, rather than just hunting simplistically for words ending in LY.