Visiting websites today means encountering cookies – those small text files stored by browsers. Cookies enable convenient features like keeping you logged into a site. But they also raise privacy questions around tracking users‘ activity. One common variety is persistent cookies, lasting from weeks to years on your device. What exactly are these long-term cookies, how do they work, and how can you manage them?
Defining Persistent Browser Cookies
When you access a website, it may place a cookie in your browser that stores data to remember you between visits. These persistent cookies remain on your device until they expire, unlike session cookies which are deleted when you close the browser.
Persistent cookies allow sites to identify and recognize repeat users and recall their preferences. According to Statista, over 90% of popular websites leverage some form of persistent tracking cookies.
Common uses of persistent cookies include:
- Storing login credentials so you stay logged into Twitter, Gmail, etc.
- Recalling your purchases in online shopping carts if you don‘t finish checkout.
- Saving your location, font size, color theme, or other settings on a site.
- Tracking user behavior for targeted advertising or analytics purposes.
Persistent cookies provide convenient continuity for users. A Statista survey found 73% of respondents preferred websites remember their details so they don‘t have to re-enter them. However, privacy advocates argue persistent cookies give sites too much insight into an individual‘s activities over time.
How Long Do Persistent Cookies Last?
Websites control how long their persistent cookies remain on your device before expiring. This retention period is set in the cookie‘s expiration date and can range from a few minutes to over two years!
For example, here are the expiration times for common persistent cookies:
- Session cookies – Exist until you close the browser. (e.g. PHPSESSID cookie used by many sites to store session data)
- Google Analytics – Up to 2 years default. Tracks visits for site analytics.
- Facebook – Up to 2 years. Logs you into the social network across devices.
- WordPress – 1 year. Remembers if you‘re logged into an account.
- New York Times – 1 year. Saves your frequency of visits.
- Amazon – 2 years. Associates your shopping cart and account history.
What factors determine a cookie‘s expiration time?
- Purpose – Analytics and ad tracking cookies typically have longer expirations up to 2 years to continue collecting user data.
- Traffic – Busy sites may opt for shorter expiration times, assuming frequent visits. Less popular sites use longer cookies for casual users.
- Engagement – Actively returning users get cookies regularly renewed. Less engaged visitors see older cookies expire sooner.
- Storage limits – Browsers restrict total cookie size, generally 4-5MB, so longer expirations help minimize this.
- Regulations – Laws like GDPR require minimizing data retention time which encourages shorter cookie lengths.
Best practice is to set cookie expiration as short as possible based on its specific purpose, while preserving a smooth user experience. For example, a recent survey of the top 200 sites found session cookies averaged only 0.42 days while tracking cookies averaged over a year!
Managing and Deleting Persistent Cookies
Want more control over the cookies stored and tracked on your devices? Here are a few options for managing persistent cookies:
- Delete manually – Clear some or all cookies directly through your browser settings or by clicking "Clear cookies" when quitting your browser.
- Set cookie rules – Browser extensions like Cookie AutoDelete let you customize when cookies expire on a per-site basis.
- Use private browsing – Private or incognito modes in Chrome, Firefox etc don‘t save cookies after you close the window.
- Block third-party cookies – Prevents cookies from advertisers, social media, and other third-party domains. Mozilla Firefox offers these granular blocking options.
- Modify browser settings – Most browsers let you configure permissions, blacklist certain sites from setting cookies, delete cookies on exit, and more.
- Leverage cookie manager tools – Extensions like Cookie Metrix provide analytics on all cookies across sites and automate cleaning them.
- Use a private DNS service – Providers like NextDNS can block known tracking domains at the network level from ever setting cookies in your browser.
Regularly clearing cookies means losing convenience features and personalization. Adjust your approach based on your comfort level with cookies.
Persistent Cookies and Online Privacy Implications
The extensive tracking capabilities of persistent cookies raise concerns around user privacy. Specific issues include:
- Cross-site tracking – Advertisers join data from cookies across multiple sites to target ads. Google logs your activity across its widespread ad network.
- Shadow profiles – Data brokers like Acxiom purchase cookie data to build profiles on non-users. You‘re tracked even without an account.
- Personal data sharing – Few sites explain what cookie data they share with affiliates and partners. This data gets beyond your control.
- Lack of awareness – Many users don‘t fully understand cookies and their privacy tradeoffs when browsing casually. Consent is questionable.
- No clear way to opt-out – Despite regulations like GDPR, most sites only allow disabling cookies entirely. No granular opt-out of individual cookie tracking.
- Hard to remove – Persistent Flash cookies re-create regular cookies if deleted. They require special removal tools.
Consumer advocates argue persistent cookies give excessive tracking capacity to advertisers with little accountability on data usage. However, cookies also provide conveniences that users take for granted. The solution likely involves responsible legislation combined with greater user awareness around online privacy.
The Future of Cookies for Online Tracking
Persistent cookies face a shifting landscape going forward. Upcoming changes include:
- Google‘s Chrome browser will phase out third-party cookies over the next few years. This disrupts the online ad industry.
- New user-level browser tracking techniques like fingerprinting provide alternatives to cookies but raise bigger privacy issues.
- Laws like the GDPR and CCPA aim to increase transparency around data collection but lack consistent enforcement so far.
- Privacy-focused browsers like DuckDuckGo offer cookie clearing on exit and built-in tracker/ad blocking. But convenience suffers for users.
- Sites may shift to shorter cookie expiration times and lean on context clues like IP addresses rather than long-term tracking.
While persistent cookies will likely remain a presence online, expectpressure from regulators, browsers, and privacy-conscious users to reduce their tracking capabilities. Sites should consider minimizing cookie lifetimes based on actual user needs. And users should stay vigilant in regularly clearing their cookies while understanding the privacy tradeoffs involved.
The Role of Cookies Online
Cookies provide both convenience and privacy concerns as tracking tools for websites. Persistent cookies lasting weeks or longer particularly stand out for their ability to identify users over time, across sites. Educating yourself on how these long-term cookies work and taking steps to actively manage them can help strike the right balance for your personal privacy preferences online.