https://www.hardforking.com/upcoming-ethereum-hardfork-constantinople/ 
Firstly don’t panic! Many people think hard forks are a bad thing, that is certainly not always the case. Most people know of hard forks from having gone through the big daddy of forks, the Bitcoin hard fork to Bitcoin Cash. Now that was a wild ride and in many respects continues to be so with battle-lines still firmly in place between the two communities. August 1st is the anniversary of that fork or the 1st birthday party for Bitcoin Cash, whatever way you want to look at it.
Ethereum has an upcoming hard fork called Constantinople. In this article we will cover why Ethereum is hardforking and give you the basics, the need to knows.