Off-chain transactions that take place may later be reported or bundled together before being sent to the main chain.
Altcoin
Altcoin is the term given to describe alternative digital assets, such as a coin or token that is not Bitcoin. This nomenclature comes from the idea that Bitcoin is the original cryptocurrency and that all others are then considered “alternate” or “alternative” coins.
In blockchain, an address refers to a unique alphanumeric identifier associated with a digital wallet or account that is used to send, receive, and store cryptocurrencies or other digital assets.
In a few words, a candidate block is a block that a mining node (miner) is trying to mine in order to receive the block reward. So a candidate block may be described as a temporary block that will be either validated or discarded by the network. Miners compete with each other to validate the next block and add it to the blockchain, but first, they have to create a candidate block to participate in the mining competition.