CF is only processed on the server (server-side) - what your
user gets in the browser is straight HTML or other potential
client-side technologies (like JS etc)
Therefore, unless you specify for the browser not to cache
images or content, the browser will manage that on its own.
If you have pages that contain dynamic content based on
queries, you can specify a cache timeout for the query so it does
not keep re-checking the data server, which will speed things up.
If you run your own server and have control over CF Admin and
you only operate a single website where pages never change much,
you can also cache templates; however that can be problematic if
you want certain pages to update with new dynamic content regulalry
- so most people have template caching turned off.