what's an NFT?
an NFT is just like any physical item that is obtainable and/or collectible (eg. a baseball card, a pair of shoes, a painting, and so on), except it is exclusively digital. but NFTs, like physical objects, still hold value. why? because you can claim them as your own and nobody else's thanks to the (blockchain) technology behind NFTs.
can't someone just download an NFT's image/video and get it for free?
well, similar to the way a baseball card expert could verify whether a certain card is legitimate or a fake, the blockchain technology these digital collectibles exist on can verify NFTs as legitimate or fake. and they can be bought/sold/traded much the same as their physical predecessors. the above scenario (downloading the same image an NFT uses) would be analogous to someone printing a famous painting and saying they own it. copies are not the original. they may appear the same, but there are ways to prove an NFTs legitimacy. this is true of physically collected items, and it's true of NFTs.
somebody could create an NFT using somebody else's artwork or imagery, but this is why different marketplaces have different systems in place to prevent theft from happening (such as user verification).
how do digital-only items have any value at all?
baseball cards, to stick with the same example, hold value because people believe they hold value. an NFT is only worth as much as people think it is worth (how much money you could get if you tried to sell it).
what started out as physical baseball cards in wax packages (with a stick of bubblegum) are now digital art pieces on a blockchain (with a lot of cool features, but no bubblegum...).
now, when it comes to NFTs, there are different places you can get them. and different places can run on different variations of the same kind of technology, and thus accept different forms of payment.
why would anybody collect something that is purely digital?
why do some people collect comic books and then never open them? why do some people buy purses that never get used?
many people collect NFTs because it's fun. some NFTs only exist in one or a few copies, which makes owning one of these NFTs something exclusive. there are also some places that offer various NFTs in packs (like booster packs of random trading cards). in these cases, there is an element of luck & chance that you could get an extremely rare NFT that only you (or a small group of people) will ever be able to own.
and undoubtedly, there are people who collect NFTs in order to flip them somewhere down the line to make a profit. as NFTs continue to grow and become more mainstream, many NFTs created early on could end up being worth a lot of money. still other NFTs are worth a lot of money immediately. official NBA NFTs (which the NBA refers to as "moments") are already selling for upwards of $100,000 depending which player the moment features.
what is a blockchain?
first, let's talk about blockchains briefly (there are longer explanations elsewhere).
to put it extremely simply, imagine you're back in grade school. within your particular school, School A, you have Class A, Class B, Class C, and so on. now, let's pretend the teachers are all creative and fun teachers, and that each class has its own currency in place that rewards students (for good behavior or whatever, it doesn't matter), and that the currency holds value amongst fellow classmates. because all Classes are at the same School, you could probably convince your buddy in a different class to accept your currency in exchange for theirs. or to buy/trade with you. even if the teachers and currency differ in some way, the overall system governing the classes (even though the classes are different in some regards) is similar enough.
your friend at School B, however, quite possibly wouldn't even know how to trade with you even if you wanted to. do teachers at School B award currency at the same rate? do they keep track of currency in the same way? are the same prizes offered in exchange for that currency? how do you know how much any of your currency is worth if the rules of both schools are unknown to each other (and could also be changing over time).
in summary, School A and School B are like different blockchains, and the currencies used in the different classrooms would be the different cryptocurrencies that use a given blockchain. the technology behind different blockchains functions differently enough to make currencies using one form of blockchain (like Bitcoin, for example), inherently incompatible with another (like Ethereum).
within each blockchain ecosystem, there is the possibility of other kinds of tokens, which store data in a way designated by the token's creator(s). tokens can represent money, NFTs, a video game character's stats, ...
for example, on the Ethereum blockchain, although "Ethereum" is the native currency on said blockchain, there are also other tokens which utilize the same technology and exist in the same ecosystem, such as Tether, Dai, Uniswap, and so on. NFTs on the Etherium blockchain are also stored and transmitted the same was as Etherium currency. the tokens just represent different things.
blockchain technology functions in such a way that it enables these tokens to be viably used as currency because, except in extenuating circumstances, you can't fake transactions. "print" fake money, or otherwise "fool" the blockchain, which is essentially a giant, decentralized ledger that stores all transactions.
what is WAX?
this article, by the creators of the WAX blockchain, explains why WAX has its own blockchain (and token). --- Why does WAX need its own protocol and blockchain?
some notable names currently operating in the WAX NFT realm are Capcom, Garbage Pail Kids, Deadmau5, Atari, and more...
AtomicHub is just one marketplace for buying/selling/trading/auctioning WAX-based NFTs.