Apay is a stellar anchor for BTC, ETH, LTC, and few other assets.
It means that Apay provides a custody service, which allows users to deposit external assets (currencies and tokens that aren't issued on Stellar) for trading on Stellar Decentralized Exchange.
You can, for example, deposit BTC, exchange it into XLM with one person, then exchange it into LTC with another person and then withdraw to your LTC address using Apay. Using Apay assets you can trade using any Stellar exchange interface, such as stellarx.com, stellarport.io, interstellar.exchange, stellarterm.com or other stellar wallets.
When you deposit external assets, such as BTC, Apay sends you the same amount of BTC token, issued on Stellar by apay.io, which you can then hold on your Stellar account, send to other users fast (5-sec finality) and free (0.00001 XLM fee), or exchange into other Stellar based assets.
Apay reserves are 100% backed by the real asset and stored securely with our trusted partners. Funds can be used for lending or other yield-generating activities and yields are passed on to users as daily payments.
Any time token issued by apay.io on Stellar can be redeemed back into the real asset.