Blockchains are decentralized systems. There is no single point of control or administration. In contrast to other IT systems, there is no admin in a blockchain. Instead, blockchains are governed.
Blockchains, depending on who can read the state and who can participate in block production (updating the state), could be classified in mainly two ways - Private or Public, and Permissionless or Permissioned.
Applications which use a decentralized backend (like a blockchain), are called Decentralized Applications or DApps.
Smart Contracts allow users to add business logic to blockchains to make them useful for several business use-cases.
A blockchain wallet is a software program or a hardware device that could be used to store cryptographic keys.
Accounts are a way of representing users on the blockchain. In a blockchain, accounts are generally a representation of a user's keys.
Block Production is the process of proposing and appending new blocks to the blockchain so that the state of the chain could be updated.
Signing is the process of associating your identity with information so that it could be verified that the information is coming from you.
Hashing is the process of deriving fixed-length strings from arbitrary-length data.
Transactions are used to propose an update to the state of the blockchain. Blocks are groups of transactions.
Blockchain node software running on a physical or virtual machine and accepting connections is a blockchain node.
In the context of blockchain, consensus is the agreement on the state of the blockchain among all the nodes in a network.
Blockchain is a system that allows two or more mutually unknown parties to reach an agreement without middlemen.