What is Hot Linking?
Hot linking is a method to prevent other websites from directly linking to your files and using your bandwidth. For instance, other websites could link to your images and videos and when people visit those websites, you will be losing some bandwidth since files from your server is being viewed.
With the help of hot linking, other websites can not use the files from your server and hence you won't be losing bandwidth anymore.
Note: If search engines or other sites linking to or displaying your site, the links will work but if the search engines or other sites just displaying images without displaying your site, the links will not work.