When browsing to a website, "who" makes makes the choice of determining whether to pull a webpage from the local cache or from the server? Is it the browser? Web server? Webpage-specific coding?
How is this determination made?
Proxy servers are known for their caching features. Maybe you are behind one.
Also many search engines will ask you if you would like to load a cached version of a page if your internet is slow and failing to render the more recent data.
Somewhat of a problem considering most content is so dynamic these days.