A testnet is a test network that allows developers and users to experiment with a decentralized applications (dapps) without publishing their contract to the main network.
A testnet uses test cryptocurrency, which has no real-world value.
The Uniswap Interface supports the following testnets:
The Labs team has limited resources to support additional testnets and decides which ones to support based on the network usage, security, and our bandwidth to maintain.
*Not currently available on the Uniswap web app
Updated