What is Ethereum?
Early blockchain technology was primarily used to store just one kind of information in every block: cryptocurrency transactions. These transactions are usually characterized by three parameters: origin address, destination address and transferred amount. All the nodes on the corresponding network are involved in the process of validating the correctness of each transaction and broadcasting them to other network peers.
The ethereum platform is built on top of blockchain technology. However each Ethereum node is provided with a virtual machine (the Ethereum Virtual Machine or EVM) which allows executing code stored in the blocks instead of simple transactions. This allows the creation of advanced decentralized applications: it brings together all the power of computer applications with all the security, censorship resistance and tamper-proof advantages from traditional Blockchain use cases.
The code stored in the blocks from the Ethereum Blockchain and executed by the EVM are also known as Smart Contracts.