What are cookies in computers?

Also known as browser cookies or tracking cookies, cookies are small, often encrypted text files, located in browser directories. They are used by web developers to help users navigate their websites efficiently and perform certain functions. Due to their core role of enhancing/enabling usability or site processes, disabling cookies may prevent users from using certain websites.

Cookies are created when a user's browser loads a particular website. The website sends information to the browser which then creates a text file. Every time the user goes back to the same website, the browser retrieves and sends this file to the website's server. Computer Cookies are created not just by the website the user is browsing but also by other websites that run ads, widgets, or other elements on the page being loaded. These cookies regulate how the ads appear or how the widgets and other elements function on the page.

Standard uses for browser cookies

Website servers set cookies to help authenticate the user if the user logs in to a secure area of the website. Login information is stored in a cookie so the user can enter and leave the website without having to re-enter the same authentication information over and over.

Session Cookies are also used by the server to store information about user page activities so users can easily pick up where they left off on the server's pages. By default, web pages really don't have any 'memory'. Cookies tell the server what pages to show the user so the user doesn't have to remember or start navigating the site all over again. Cookies act as a sort of ¿bookmark¿ within the site. Similarly, cookies can store ordering information needed to make shopping carts work instead of forcing the user to remember all the items the user put in the shopping cart.

Persistent or tracking Cookies are also employed to store user preferences. Many websites allow the user to customize how information is presented through site layouts or themes. These changes make the site easier to navigate and/or lets user leave a part of the user's ¿personality¿ at the site. 

Cookie security and privacy issues

Cookies are NOT viruses. Cookies use a plain text format. They are not compiled pieces of code so they cannot be executed nor are they self-executing. Accordingly, they cannot make copies of themselves and spread to other networks to execute and replicate again. Since they cannot perform these functions, they fall outside the standard virus definition.

Cookies CAN be used for malicious purposes though. Since they store information about a user's browsing preferences and history, both on a specific site and browsing among several sites, cookies can be used to act as a form of spyware. Many anti-spyware products are well aware of this problem and routinely flag cookies as candidates for deletion after standard virus and/or spyware scans.See here for some privacy issues and concerns.

The way responsible and ethical web developers deal with privacy issues caused by cookie tracking is by including clear descriptions of how cookies are deployed on their site. These privacy policies should explain what kind of information is collected and how the information is used.

Other cookie-based threats

Since identity protection is highly valued and is every internet users right , it pays to be aware of what threat cookies can pose.

As cookies are transmitted back and forth between a browser and website, if an attacker or unauthorized person gets in between the data transmission, the sensitive cookie information can be intercepted. Although relatively rare, this can happen if the browser is connecting to the server using an unencrypted network like an non-secured WiFi channel. Internet security is only attainable if you regualrly use a anti-virus protection programme.

Other cookie-based attacks involve exploiting faulty cookie-setting systems on servers. If a website doesn't require browsers to use encrypted channels only, attackers can use this vulnerability to trick browsers into sending sensitive information over insecure channels. The attackers then siphon off the sensitive data for unauthorized access purposes.