Smart contracts are self-executing digital agreements where the contract terms are written directly into lines of code. These contracts enforce and execute the agreed conditions automatically once the set triggers are met, which, in turn, eliminates intermediaries such as lawyers or brokers. Operating on blockchain platforms, smart contracts ensure a secure, decentralized, and immutable environment. Thus, it is necessary for trustless and automated transactions. Their usage ranges from health and aviation to banking, enabling smoother processes, increased transparency, and reduced operational costs. This chapter provides a broad overview of smart contracts, discussing their capabilities, their applications, and the tremendous business effects they generate within different industries. It describes how smart contracts revolve around traditional business by automating more complex processes and making sure that agreements are executed without human interference. It further deliberates on the evolution of blockchain technology, mapping its development right from the initial Blockchain 1.0 model, mainly to support cryptocurrencies to the advanced public permissionless and private permissionless blockchain models that eventually came to support a wide range of decentralized applications, including smart contracts. This chapter also covers some of the available platforms used for smart contract development, including Ethereum, Binance Smart Chain, Cardano, and Solana. Each of the platforms is reviewed on its distinctive features, strengths, and applications for which it is best suited. The chapter also discusses the challenges of smart contract implementation and, most importantly, the security risks and vulnerabilities associated with the operation of the blockchain network. It outlines common attacks such as reentrancy attacks and timestamp dependence and provides ideas related to methodologies on how such risks can be minimized. As blockchain technology continues to evolve, smart contracts are positioned to be at the forefront of digital transactions, governance, and innovation in the future. Their secure, automated, and trustless interactions will turn out to be of paramount importance during attempts to sail through the broad and exponentially changing decentralized technology space. Therefore, this chapter stands as an important primer for understanding the significance of smart contracts and their implications for the modern-day digital economy.