1. Blockchain is a chained data structure, which combines data blocks in an orderly way according to time sequence, and cryptographically guarantees that it is an unbreakable and unforgeable distributed ledger.

2. Blockchain is a historical record of transactions, much like a database. A block in a chain is equivalent to a page in a book. Every page in the book contains words and stories, and each page has its own information: title, chapter name, page number and so on.

3. In the blockchain, each block has a title, which contains data about the block, such as technical information, reference to the previous block, digital fingerprint (also called "hash") of the data contained in the block, and so on. This hash is very important for sorting and block verification.