Smart contracts are self-executing lines of code with the terms of an agreement between buyer and seller being automatically verified and executed via a computer network. Invented by Nick Szabo, an American computer scientist, in 1998, smart contracts are a part of the blockchain technology.

Smart contracts are digital contracts that are written using computer programming language and then stored and executed on the blockchain, or a public digital ledger. The terms of the contract are fulfilled when certain criteria are met – thus, a smart contract can perform a variety of tasks from simple payments to complex stock options trading.

Smart contracts can be used for a variety of purposes, from the traditional financial and contractual to entertainment, governmental, and even healthcare applications. They can be used in everything from insurance to rent payments, mortgages, and much more. Smart contracts are highly secure and cannot be altered because they are stored on the blockchain. This also makes them transparent, as every transaction is easily viewable and traceable by anyone with access to the blockchain.

Thanks to their automated features, smart contracts are also faster and more cost-efficient than traditional contracts. This is because they do away with the need for intermediaries and lengthy processes, eliminating the risks of human error in the process. They are also resistant to fraud because they are executed automatically once certain conditions are met, making them virtually unchangeable.

In conclusion, smart contracts are revolutionary pieces of technology that could change the way we do business by drastically improving the speed, efficiency, and security of digital transactions. Despite their promising potential, however, there are still a few kinks to be ironed out such as the difficulty in creating and managing complex digital contracts. Regardless, smart contracts are set to revolutionize the way we transact and sign deals in the digital era.