A hard fork is an update to the blockchain protocol that will force its users and nodes to update if they want to continue to be part of the ecosystem. A soft fork is an update in the protocol that does not conflict with the current version. This type of fork is not mandatory within its users. It is very tricky to conduct a fork within a decentralized system since those connected to the ecosystem such as miners would have to unanimously agree with the upcoming update.
On August 1st, Bitcoin (BTC) experienced a hard fork which created a new cryptocurrency called Bitcoin Cash (BCH). The differences between the developers and miners were purely technical.
Upcoming Ethereum Hard Fork
The “Metropolis” hard fork of Ethereum (ETH) is anticipated towards the end of September 2017. This will bring more anonymity to the blockchain, increase security, easier smart contract programming (more application adoption) but more importantly transition from proof of work to proof of stake on the network. This being said, there are no immediate concerns of alternate Ethereum (ETH) based coin being created. There is a consensus among the community towards this update. As far as price changes, it is unknown as to the potential effects. Less mining could drive down the price but an improved ecosystem can bring more investment. If you possess ETH, make sure to keep them in a hardware wallet to mitigate any potential security issues.