The Internet of Things (IoT) is revolutionizing human life with the idea of interconnecting everyday used devices (Things) and making them 'smart'. By establishing a communication network between devices, the IoT system aids in automating tasks and making them efficient and powerful. The sensors and the physical world, connected over a network, involve a massive amount of data. The data collection and sharing possess a critical threat of being stolen and manipulated over the network. These inadequate data security and privacy issues in IoT systems raise concerns about maintaining authentication of IoT data. Blockchain, a tempter-resistant ledger, has emerged as a viable alternative to provide security features. Blockchain technologies with decentralized structures can help resolve IoT structure issues and protect against a single point of failure. While providing robust security features, Blockchain also bears various critical challenges in the IoT environment to adapt. This paper presents a survey on state-of-the-art Blockchain technologies focusing on IoT applications. With Blockchain protocols and data structures, the IoT applications are outlined, along with possible advancements and modifications.