Browsing the web can seem like a passive, one-way experience in which the user simply looks at web pages on the internet. In fact, however, the user's web browser is continually downloading and storing information from the internet. Cookies are one example of this kind of downloading; files stored in the browser's cache are another. The two types of file are similar in some ways, but perform different functions.
Every time a web user accesses a new web page, all the information on the page is downloaded over their internet connection and displayed in the web browser. With some sites, this can be quite a lot of data. In order to avoid having to download this new data every time a new page is accessed, the web browser stores the page files in a folder called a cache.
Function of a browser cache
The files stored in a browser cache allow users to visit pages that they have previously visited without downloading all the data every time they do so. Only data which has changed since the cache was last updated needs to be downloaded. For instance, if a user navigates to a new page and then quickly clicks the Back button, the previous page will be displayed from the browser's cache, rather than from the internet. This use of stored files allows the browser to display the page much more quickly than if it had to be completely reloaded.
Like files stored in a browser cache, cookies are files downloaded from the internet by the web browser. The main difference is that cookies are sent to the user by a site they are visiting. The presence of the cookie on the user's computer allows the site to track the user's interaction with the site. By setting a cookie on a user's computer, a website can know, for instance, that the user is returning to the site and has already logged in. Some cookies last only for a short time, such as a single visit to a site, while others can last indefinitely.
Similarities and differences
Both cookies and the files stored in a browser cache are ways of making a user's web-browsing experience simpler and quicker. Both are files downloaded from the internet and stored by the browser. The key difference is that the web browser not only stores a cookie but uses it to communicate with a site, providing information about the user. Online privacy advocates recommend that users periodically delete the cookies and files stored by their browsers, since these files provide a record of the user's browsing habits that anyone with access to the computer can see.