NFT stands for a non-fungible token, which means that hidden in those quirky artworks, there is a totally unique and non-interchangeable unit of data stored on a digital ledger that uses blockchain technology to establish proof of ownership. NFTs are collectable digital assets that hold value, just like how physical art holds value, so do NFTs.
NFTs are a lot like cryptocurrencies such as Bitcoin and Ethereum. However, an NFT is completely unique, and it can't be exchanged like-for-like, which is where non-fungible starts to make sense. The file stores extra information that elevates it above pure currency and brings it into the realm of, well, anything, really.
Any kind of easily reproduced digital file can be stored as an NFT to identify the original copy, like photography, art, music, videos, tweets, and even memes. You can make NFTs from almost anything unique that can be stored digitally and holds value. They're like any other collector's item, like a painting or a vintage action figure, but instead of buying a physical item, you're instead paying for a file and proof that you own the original copy.