MongoDB

 MongoDB is an open source, document-based database management system that does not require a table schema description. MongoDB - classified as NoSQL and uses JSON-like documents and a database schema. If all four previous DBMSs are well known to most IT professionals, then few have heard of MongoDB. But she confidently takes the 5th line in almost all ratings. And as a result, in our ranking, she also occupies the 5th position.

What is Proof of Work (PoW)?

 What is Proof of Work (PoW)?

Back in 1993, two IBM analysts Cynthia Wark and Moni Naor published a scientific article in which they stated that it would be possible to provide access to certain network resources only if the most complex tasks were performed.

In May 1996, British cryptographer and developer Adam Back was able to implement this concept into a technology called Hashcash, used in online systems to protect against spam attacks. Then he did not even suspect that he laid the foundation for the creation of digital currencies.

In 1999, the term PoW was designated as a unique principle for protecting network systems, with which you can effectively protect yourself from powerful dos-attacks.

In 2004, developer Satoshi Nakamoto integrated Hashcash into Bitcoin, which became the first digital currency to use the concept of PoW.