The browsers cache a webpage on your machine when it is loaded, and on subsequent request show the data from the cache instead of requesting the server. You can instruct the browser to load the most recent version of the page from the server (called Hard Refresh) by the following steps.
Mozilla Firefox
Windows:
Hold the Ctrl key and press the F5 key or, hold down Ctrl and ⇧ Shift and then press R.
Mac:
Hold down the ⇧ Shift and click the Reload button or, hold down ⌘ Cmd and ⇧ Shift and then press R.
Google Chrome
Windows:
Hold down Ctrl and click the Reload button or, press F5.
Mac:
Hold ⇧ Shift and click the Reload button or, hold down ⌘ Cmd and ⇧ Shift key and then press R.
Internet Explorer
Hold the Ctrl key and press the F5 key or, hold the Ctrl key and click the Refresh button.
Safari
Hold down ⇧ Shift and click the Reload button on the toolbar.