MetaMask

MetaMask is a web browser extension and mobile app that allows you to manage your Ethereum private keys. By doing so, it serves as a wallet for Ether and other tokens, and allows you to interact with decentralized applications, or dapps. Unlike some wallets, MetaMask keeps no information on you: not your email address, not your password, and not your Secret Recovery Phrase or other private keys. You retain all power over your crypto-identity.[1]

Metamask

MetaMask Flask

MetaMask Flask is an experimental playground for developers, where new or proposed features can be rolled out and tested before deploying them to the broader public.

MetaMask Snaps

Snaps is a system that allows anyone to safely expand the capabilities of MetaMask. A "snap" is a program that we run in an isolated environment that can customize the wallet experience. For example, a snap can add new APIs to MetaMask, add support for different blockchain protocols, or modify existing functionality using internal APIs.

Snaps are run in an isolated environment where they have access to a limited set of capabilities, determined by the permissions they were granted by the user during installation

Sources

MetaMask website

Metamask Flask

Metamask Snaps documentation