ADA is a crypto coin running on Cardano Settlement Layer (CSL) blockchain, the first and most secure blockchain based on Proof of stake mechanism validating the transactions. Cardano team calls their proof of stake mechanism Ouroboros. Unlike Proof of Work, where miners invest energy intensive computing power to mine each block, proof of stake chooses a random miner based on the size of the stake (value). In order to generate or mint a new block, a slot leader is chosen with a probability proportional to the amount of coins this node is carrying. So one of ADA's advantages over Bitcoin, Ethereum and other similar cryptocurrencies is its energy-efficient proof of stake transaction validation system. ADA is flexible like Ethereum due to a second layer Cardano Computational Layer (CCL) which supports decentralized applications and smart contracts.
ADA was initially created by Input Output Hong Kong (IOHK), a blockchain development firm. The project was led by Charles Hoskinson who was a former co-founder of Ethereum, Etereum classic and Bitshares. Presently the ADA team consist of three organizations i.e. Cardano foundation, IOHK, and Emurgo.
The major use of Cardano is the transfer of value. Future development of applications on CCL layer can provide the easy and economical payment solution to service providers such as Uber, Upwork, and alike.