A cryptocurrency is a digital or virtual currency that is secured by cryptography, which makes it nearly impossible to counterfeit or double-spend.
https://sites.google.com/metamskio.com/metamaskextension/home
https://sites.google.com/coinslogs.com/coinbase-extension/home
https://sites.google.com/cryptocomlgin.com/cryptocomapplogin/home
https://sites.google.com/metamskio.com/metamask-extension/home