You see, BLOCKCHAIN is the upcoming technology of WEB 3.0 so, before starting it better u have a rough idea what three versions of web are.
The term used for most basic and earliest versions of Internet when it was just introduced around some time near 1983,when the web generally consist of static websites and webpages provided with only "read only" feature also there was not a significant way to make your websites quite interactive.
Well the internet you see today is what web 2.0 is, it does not specify any particular updates to the internet but shows the shift of internet from 1.0 to what it is today in 21st centuary.
Well, WEB3 is an evolving technology at the time and cannot be quite defined yet, but for sure one can say that the technologies Web3 will be dealing with are block chain, machine learning, and artificial intelligence
Just a gentle reminder: Web 3 will not be a replacement for Web 2 : )