Blockchain, also known as distributed ledger technology, has gained widespread adoption in many fields apart from financial transactions. With high security and transparency, it is used in supply chain management systems, healthcare, payments, business, Internet of Things (IoT), voting systems, and many more for securing a wide range of digital assets from tampering. Blockchain technology is also used to share, replicate, and synchronize data, and to track transactions and assets in any type of business across different geographical locations. Rather than working with a central authority to control all the data transactions, blockchain technology uses a consensus mechanism, where all the nodes of the system need to agree on a new transaction. At first, this chapter discusses all the fundamental aspects and technical details along with the advantages and disadvantages of blockchain. It also discusses different types of blockchain networks with their pros and cons, smart contracts, and hyperledger technology. Then, several applications of blockchain technology and challenges in adopting it in various industries are also given in this chapter to show how the technology works as a whole.