storage (caching) of web documents, such as HTML pages and images, to reduce bandwidth usage, server load, and perceived lag. A web cache stores copies of documents passing through it; subsequent requests may be satisﬁed from the cache if certain conditions are met.”
posts, aggregated data such as ratings or reviews (“likes”). • Uncacheable: secure, private, personal data such as user login information, credit card info, etc. Data that must change rapidly—stock quotes, for example, or health monitoring systems.
the HTML page. • <script> <style> <img> etc. tags reference static content on the CDN • User’s browsers loads (and often stores) the static content locally, because it’s served with a Cache-Control: max-age=32767 header.