Quick answer: what clearing cache does
Clearing your browser cache forces your device to download the newest version of a page, including updated images, styles, scripts, and content. It is useful when a change has been published but your browser keeps showing the old version.
A browser cache is not bad. It helps websites load faster. The trouble starts when the saved version is older than the live page, especially after a redesign, plugin update, DNS change, or launch.
Google Chrome
Windows: Ctrl + F5
Mac: Cmd + Shift + R
Safari
Mac: open the Safari menu, choose Settings, enable the Develop menu if needed, choose Empty Caches, then reload with Cmd + R.
Mozilla Firefox
Windows: Ctrl + F5
Mac: Cmd + Shift + R
Microsoft Edge
Windows: use Ctrl + F5. On Mac, use Cmd + Shift + R to request a fresh copy of the page.
Mobile browsers
On phones and tablets, close the browser tab, reopen the page, and if needed clear website data for the browser. For Safari on iPhone, this is under Settings, Safari, Advanced, Website Data. For Chrome, use Settings, Privacy and Security, Clear Browsing Data.