Cookies, the little files that web browsers allow websites to place on visitors’ computers, are enormously beneficial for both site creators and site visitors but sometimes get a bad rap by those who don’t understand them. Cookies are often lumped in with spyware and feared to be a mechanism for “hackers” or those with malicious intent to get sensitive information from a user’s computer. In truth cookies can only hold information that a user provides to a website and can only be read by the website that placed the cookie.

As evidence of users’ beliefs that cookies are bad, research advisory organization JupiterResearch reports that almost 60 percent of American Internet users have deleted cookies from their computers. 10 percent are deleting cookies daily. 17 percent are deleting cookies weekly. And 12 percent are deleting cookies monthly. This means 39 percent of users have deleted their cookies within any given month.

“Advertisers using lifetime value metrics need to reexamine how accurate that data is,” said Eric Petersen, the lead analyst on the JupiterResearch report. “The further away you get from the date the cookie was set, the less likely that the information is completely accurate.”

If the deleting-cookies trend continues, there are several adverse consequences for advertisers.

1. The same ads will be shown to a single user because the user will appear to be a new visitor who has not yet seen a given ad, which results in advertisers spending more money to deliver ads multiple times
2. The delivery of targeted ads (based on a user’s preferences and browsing habits) will be increasingly difficult
3. Website traffic statistics and campaign metrics will become increasingly less accurate as repeat visitors or leads are mistakenly marked as new visitors or leads

Although some early claims suggest Macromedia’s Flash platform has potential for remedying this situation, other reports suggest that Firefox and other browsers don’t support this fix. The only suggestion that seems to have any true merit is to move toward first-party cookies (set by the site the user is visiting) rather than third-party cookies (set remotely by a site other than that being visited).

Coremetrics research found that 13.8 percent of traffic on e-tailers websites that use third-party cookies is anonymous traffic. Retail sites that set their own cookies have only 0.8 percent anonymous cookies, suggesting that users are deleting third-party cookies at a higher rate than first-party cookies.

Unfortunately, there isn’t much else to do at this point but continue to monitor the situation and recognize that reliance on cookies for accurate metrics is currently at risk.

For more information

The Web Cookie is Crumbling

Third-Party Cookies Crumble for E-Tailers

Consumers Delete Cookies at Surprising Rate