Websites are periodically updated by their owners.
All widely used Internet browsers save in the terminal (PC) some data of the website in order to improve surfing speed in future visits.
But if such data is subsequently updated (modified) by the website owner, it will not be consistent with the obsolete data saved in your PC, meaning that you may find errors or malfunctioning while surfing on the web.
This is easily amended by eliminating in your browser the obsolete data, operation called here Browser Cleaning. This cleaning does not imply any peril but on the contrary, it is a highly recommended practice that should be carried out periodically.
The cleaning procedure differs according to the browser used. If your browser is one of the four shown below, click on the corresponding button and follow the cleaning instructions. If you use a different browser hopefully you will not find difficulties in finding the cleaning instructions for it.