Iako je robustan i siguran, Proof of Work mehanizam konsenzusa suočava se s izazovima poput skalabilnosti, centralizacije, dostupnosti te negativnog utjecaja na okoliš. Samim time pojavila se potreba za alternativnim metodama konsenzusa. Proof of Stake i njegove varijacije nameću se kao rješenje. Konsenzusi obrađeni u radu su redom: Proof of Stake, Proof of Activity, Delegated Proof of Stake, Proof of Authority, Pure Proof of Stake te Proof of History. Svaki od navedenih pokušava, uz dodatne tehnologije razvijene oko mehanizma, riješiti probleme Proof of Work konsenzusa. Pojavom PoS konsenzusa i njegovih varijacija povećana je dostupnost za pojedinca da se uključi u rad mreže. Potrošnja energije je uvelike smanjena i generira se manje elektroničkog otpada. Skalabilnost se poboljšala u odnosu na PoW. Centraliziranost je jedan od izazova gdje bi se u budućnosti mogao vidjeti najveći napredak. U praktičnom dijelu rada, istraživanjem Solana blockchaina zaključili smo da je poprilično centraliziran. Although robust and secure, the Proof of Work consensus mechanism faces challenges such as scalability, centralization, availability and negative environmental impact. Therefore, the need for alternative methods of consensus arose. The Proof of Stake and its variations are imposed as a solution. The consensuses discussed in the thesis are: Proof of Stake, Proof of Activity, Delegated Proof of Stake, Proof of Authority, Pure Proof of Stake and Proof of History, respectively. Each of the attempts above, with additional technologies developed around the mechanism, to solve the problems of the Proof of Work consensus. PoS consensus and its variations have increased the availability for the individual to get involved in the work of the network. Energy consumption is greatly reduced and less electronic waste is generated. Scalability has improved compared to PoW. Centralization is one of the challenges where the greatest progress could be seen in the future. In the practical part of the thesis, by researching Solana blockchain, we concluded that it is quite centralized.