The primary use of Smart Contracts in blockchain is to automate the execution of agreements without the need for intermediaries. These self-executing contracts contain the terms of the agreement directly written into code, which automatically enforces and executes actions when predetermined conditions are met. This innovation enhances trust and security by providing a transparent and immutable record of transactions. Smart contracts are commonly used in various applications such as DeFi, supply chain management, and real estate, facilitating faster and more efficient processes while reducing costs and potential disputes.