Client side caches are usually used to avoid transferring the same data over the network repeatedly. It can reduce network traffic and latency, then help users save money especially when they are paying for the data.
Server side caches are generally used to avoid making expensive database operations repeatedly to serve up the same content to lots of different clients.
Many big companies spend tons of money to build farms of servers to replicate their content to make access faster and both client side caches and server side caches are used in industry production environment.
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