Blockchain & Cryptocurrency

I remember a time when cryptocurrency suddenly become a topic a discussion for so many people and suddenly the it was the hot topic on the internet. Our conversation revolves around what is a cryptocurrency? And how did it got started? how does it work? How is it different from traditional currencies like USD, Euro or Rupees? What is the need for technology like crypto? The underlying technology for cryptocurrencies is blockchain and its  functions in order to verify the accuracy of transactions. How does it actually work?