The blockchain technology first emerged with the Bitcoin whitepaper, which was the first successful proposal to implement a decentralized digital currency with ability to execute completely non-reversible transactions without a trusted and centralized third party. Blockchain concept provided an inherent part of this decentralization together with hash-based proof-of-work, public key cryptography, and peer-to-peer network. Even though blockchain technology was introduced to solve the doublespending problem of electronic money without relying on a trusted third party, this particular concept is being researched and already used to solve problems in many other areas. This paper captures concepts of blockchain, its applications, issues, and suggested improvements referring to blockchain-related subsequent publications.