• Mudapaka satish kumar
• Dr V.Naga lakshmi

Blockchain is a chain of blocks where each block contains data of value without any central supervision. It is cryptographically secure and immutable. A Blockchain is a diary that is almost impossible to forge. Each block consists of Index, Timestamp, Data, Previous Hash, Hash. Blockchain databases consist of several decentralized nodes. Each node participates in administration: all nodes verify new additions to the blockchain, and are capable of entering new data into the database. Blockchain-based applications are springing up, covering numerous Fields including financial services, reputation system and Internet of Things (IoT), and so on. However, there are still many challenges of blockchain technology such as scalability and security problems waiting to be overcome. This paper presents a comprehensive overview on blockchain technology. We provide an overview of blockchain architecture firstly and compare some typical consensus algorithms used in different blockchains.

Bitcoin, Hash, Genesis Block, SHA-256

"WORKING OF BLOCKCHAIN TECHNOLOGY", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 5, page no.75-79, May-2019, Available :http://www.jetir.org/papers/JETIR1905515.pdf

"WORKING OF BLOCKCHAIN TECHNOLOGY", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 5, page no. pp75-79, May-2019, Available at : http://www.jetir.org/papers/JETIR1905515.pdf