Explain whether a single Memcache instance may be shared between numerous PHP projects.

Yes, a single instance of Memcache can be shared across numerous projects. Memcache is a memory cache that can be installed on one or more servers. You can also set your client to communicate with a certain set of instances. So, on the same host, you can run two distinct Memcache processes that are fully independent. Unless you’ve partitioned your data, you’ll need to know which instance to obtain the data from or which instance to put it into.