Blockchain is a distributed and immutable ledger allowing you to track anything, including tangible or intangible goods. This enables users or organizations to digitally and securely record entries, which are in turn endorsed and secured by a community of users.
Check out this lightboard video with Sai Vennam from IBM Cloud as he takes a deep dive into blockchain technology and covers everything from smart contracts to permissioned and permissionless blockchains
Learn more about Blockchain technology: https://www.ibm.com/blockchain/what-is-blockchain
Check out this blog on the different types of Blockchain: https://www.ibm.com/blogs/blockchain/2018/10/public-versus-private-what-to-know-before-getting-started-with-blockchain