What is Proof of Stake?
Proof of stake (POS) is the algorithm, which prevents a network (Blockchain) from possible attacks like DDOS or spam actions. First of all, It is necessary to realize that the Proof of Stake is based on the Proof of Work (POW) concept. So, you really need to understand, what is Proof of Work and how it works. After that, you start exploring Proof of Stake. POS was first described at 2009 on Bitcoin talk post. This idea wanted to solve the main shortcomings of Proof of Work and adds some other new interesting features.