Lisk is known by the letters LSK when making transactions. It is one of many cryptocurrencies - or virtual currencies - available online today. It works on a blockchain platform in much the same manner as other virtual currencies do. The transactions are secure and very quick too - you can expect to make a transaction using LSK in around 10 seconds. Upon completion, the transaction cannot be revoked.
Anyone with the Lisk app can customize how they use LSK, thanks to the sidechains that work alongside the blockchain method of transactions. This allows for a more personalized way of using the cryptocurrency, if such a thing is required.