The process I just described can also happen without someone trying to compromise the data on the blockchain. As the blockchain network grows, it is possible for multiple peers to create a new block at nearly the same time with the same block height (that is, the number of blocks preceding a particular block). This type of event is called an accidental fork. Initially, both blocks are accepted by the majority of the network. However, it is logically resolved when consecutive block(s) are added and one of the chains becomes longer than the alternative(s).
The following diagram shows two of these forks and how they are resolved: