As far as my concerns go, I am interested in the web application layer, maybe the db layer.
It’s about performance and cost.
A really good video from roadmap.sh about Web Cache and HTTP Caching Headers here. Server level/Application level caching, for example redis or memcached. Or client side. Reduces latency, cuts down the bandwidth, reduced load on the server.
Three locations: browser cache, proxy server cache, reverse proxy server cache.
Caching headers: expires, pragma, content-control
The preferred caching header is the Cache-Control header
Validator headers: etag, if-none-match, last-modified, if-modified-since