Digital money for everyday use

Digital representations of traditional fiat currencies like the US Dollar. You can purchase them at a 1:1 ratio with fiat and later redeem them with the issuer for the original underlying currency, which is held in reserves to back the stablecoin's value.

These stablecoins are backed by other crypto assets, like ETH. Their price depends on the value of the underlying asset (or collateral), which can be volatile. Because ETH's value can fluctuate, these stablecoins are overcollateralised to ensure the price stays as stable as possible. This means it's closer to say that a $1 crypto backed stablecoin has an underlying crypto asset worth at least $2. So if the price of ETH drops, more ETH must be used to back the stablecoin, else the stablecoins will lose their value. Note that some crypto-backed stablecoins like DAI also use centralized stablecoins as part of their backing.

Like fiat-backed coins, instead these stablecoins use resources like gold to maintain their value. These are 'stable' in that their price is consistently pegged to the value of another asset, and are akin to onchain ownership tracking of real-world assets

These stablecoins aren't backed by any other asset. Instead an algorithm will sell tokens if the price falls below the desired value and supply tokens if the value goes beyond the desired amount. Because the number of these tokens in circulation changes regularly, the number of tokens you own will change, but will always reflect your share.