Website cookies are small pieces of text that a website asks a browser to store. The browser sends relevant cookies back with later requests, allowing the site to remember state such as a login, a shopping basket, language settings or a consent choice. Other cookies measure behaviour or support advertising, so their purpose determines how they should be managed.
A cookie usually contains a name, a value and controls such as its domain, path, expiry, SameSite policy and security flags. It may hold a preference directly or carry an identifier that connects the browser to information stored on a server.
How do website cookies work?
- A website creates the cookie. The server can send it in an HTTP response, or approved site code can create it in the browser.
- The browser stores it with rules. Attributes such as domain, path, expiry, Secure, HttpOnly and SameSite determine where the cookie can be used and how it is protected.
- The browser returns matching cookies. On a later request to the relevant site, the browser can send the cookie back so the service recognises the session or preference.
- The website acts on the value. It may keep a user signed in, retain a basket, apply a language choice, measure aggregate use or decide whether a tag is allowed to load.
Cookies cannot read arbitrary files from a device, and the browser limits when they are sent. The main privacy risk comes from how identifiers are combined with server-side data, especially when activity is linked across sites, devices or long periods.
What are cookies used for?
- Essential operation. Authentication, security, shopping baskets, load balancing and other functions needed to provide a service the user requests.
- Preferences. Language, region, accessibility settings, display choices and other ways a site remembers how a visitor wants it to work.
- Analytics and performance. Information about visits, page use, errors and speed that helps an organisation improve its website or service.
- Advertising and measurement. Identifiers that support ad delivery, attribution, frequency control, profiling or activity linked across websites.
Purpose matters more than the cookie’s name or lifespan. A first-party cookie can still support tracking, while a narrowly configured analytics cookie may qualify for a UK PECR exception. Each cookie should be classified by what it actually does and which systems receive its data.
Types of Cookies: Session, Persistent, First- and Third-Party
Session Cookies
Session cookies last for a browser session and normally disappear when that session ends. They often keep a visitor signed in or retain a basket while the visitor moves between pages. Session length does not determine whether consent is needed. Purpose does.
Persistent Cookies
Persistent cookies remain until their expiry date or until a user removes them. They can remember preferences or recognise a returning browser across several sessions. Their lifetime should be proportionate to their purpose and disclosed clearly.
First-party Cookies
First-party cookies are associated with the site shown in the browser’s address bar. They can support essential functions, preferences, analytics or advertising. First-party does not automatically mean essential, private or exempt from consent.
Third-party Cookies
Third-party cookies are associated with a different domain from the one a visitor is viewing. Advertising and embedded services have often used them to recognise browsers across websites. Browser settings and privacy protections increasingly restrict them, but their availability does not remove an organisation’s consent obligations.
Cross-domain cookies and identifiers
A browser does not normally let one unrelated domain read another domain’s cookie. Cross-domain cookies and shared identifiers describe methods used to coordinate a session, identity or consent choice across related properties. This may involve a shared parent domain, redirects or server-side identity matching
Cookies & User Experience: Benefits Drawbacks
Web cookies offer many benefits for organizations and users:
- Enhanced user experience: Cookies remember user preferences, such as language settings and themes, providing a more personalized browsing experience
- Session management: Cookies keep users logged in and remembered as they navigate through a website
- Analytics and performance tracking: They help organizations collect data on user behavior, allowing for improvements to site functionality and content
- Targeted advertising: Cookies allow for more relevant and personalized advertising by tracking browsing habits and user interest, increasing the effectiveness of ads.
However, we are starting to see the drawbacks of browser cookies as well…
- Intrusive advertising: Cookies enable targeted ads, but some users find this invasive and annoying
- Storage issues: Accumulation of cookies can take up storage space and potentially slow down browser performance
- Security risks: If cookies are intercepted or manipulated, sensitive information could be compromised
- Privacy concerns: Cookies can track user behavior across multiple sites, leading to concerns about data collection and its potential misuse
- Regulatory compliance: Managing cookies to comply with privacy laws (like GDPR or CCPA) can be complex for website owners, particularly as more laws are enacted globally.
What do cookies track?
Cookies can store information directly or carry an identifier that links a browser to data held elsewhere.
Depending on the purpose, that information may include:
- a session ID, account state or basket reference
- language, region, accessibility or display preferences
- pages viewed, buttons selected, time on page and referral source
- ad clicks, campaign attribution and frequency information
- browser, device and approximate location data linked to an identifier
- a record of the user’s cookie or tracking preferences
A cookie does not automatically reveal a person’s name or complete browsing history. However, a pseudonymous identifier can still be personal data when an organisation can use it, alone or with other information, to single someone out or build a profile.
Privacy Concerns & Cookie Regulation
Across the globe, more and more comprehensive privacy laws are being considered and enacted, meaning cookies are becoming more regulated to protect the privacy of web users.
Cookies can collect a lot of personal information about a user, allowing organizations to track them across the web and create detailed profiles on their interests. There has been a lot of pushback in recent years as users find this increasingly invasive in their online lives, wanting instead to be in control of what data is collected and stored by companies.
As it stands, compliant cookie banners allow for compliance across websites, letting users choose all cookies apart from essential cookies (in an ideal world). However, this can often lead to consent fatigue, as users constantly have to accept and decline new cookies as they browse around the web, quite often from the same website.
Are website cookies safe?
Cookies are passive text, so they cannot install software or execute code by themselves. Risks arise when a sensitive cookie is stolen, sent over an insecure connection, exposed to scripts that do not need it or retained for longer than necessary. Secure, HttpOnly and SameSite attributes help reduce those risks, but they do not replace access controls, encryption, appropriate expiry settings and regular testing.
Do all cookies require consent?
No. The answer depends on the visitor’s jurisdiction and the cookie’s purpose. In the UK, PECR generally requires consent before information is stored on or read from a user’s device unless a specific exception applies. The exceptions are narrow, and an organisation must still comply with UK GDPR where personal data is processed.
The Data (Use and Access) Act 2025 expanded the UK exceptions from 5 February 2026. The five PECR exceptions now cover:
- the transmission of a communication
- storage or access that is strictly necessary to provide a service the user requests
- aggregate statistics used solely to improve the service or website
- appearance or functionality adapted solely to a user’s preference
- location used solely to provide emergency assistance
The statistical and appearance exceptions require clear information and a simple, free way to object. Advertising, cross-site tracking and analytics used for profiling do not fit those exceptions and still require consent. Read Syrenis’ overview of the Data (Use and Access) Act 2025 for the practical implications.
Are third-party cookies being phased out?
Not through a universal Chrome deadline. In April 2025, Google said it would maintain its existing approach to third-party cookie choice in Chrome and would not introduce a new standalone prompt. Chrome users can manage the setting, while Incognito mode blocks third-party cookies by default. Other browsers and privacy settings also restrict cross-site tracking.
Organisations should therefore avoid planning around a single phase-out date. A durable approach uses first-party relationships, honours regional consent and opt-out rules, and continues to work when a browser or visitor blocks third-party cookies.
Future of Cookies: Alternatives & Technological Advances
The cookie-less future has been threatened for the last couple of years, as Google attempts to make a move away from third-party cookies. But what does this mean for the future of tracking users across the web?
New privacy-centric alternatives are becoming the norm, as technologies like Google’s Privacy Sandbox aim to deliver targeted ads without compromising user data. This means that organizations will have to rely more heavily on first-party data, collecting and retaining data directly from user interactions on websites.
Having an effective consent management platform will allow for enhanced user control and transparency over what data is being stored and used, allowing users to change their preferences at any time.
Balancing Convenience & Privacy
Cookies play a crucial role in the functionality and personalization of web experiences. From session management and user preference storage to targeted advertising and analytics, they offer numerous benefits. However, this needs to be balanced with the rise of significant privacy concerns and security risks. There is now increased regulatory scrutiny and push for privacy-centric alternatives.
As technology evolves, balancing the advantages of cookies with the need for user privacy and compliance will be essential. Adopting effective consent management practices and exploring new tracking technologies will help organizations navigate the future of web cookies responsibly.
What is Google Consent Mode v2?
Google Consent Mode v2 lets Google tags adjust their behaviour in response to consent states for analytics and advertising. It uses four core signals: analytics_storage, ad_storage, ad_user_data and ad_personalization. Sites should set a default state before measurement commands run, then update it as soon as the visitor makes or changes a choice.
Consent Mode does not collect or store the visitor’s choice by itself. A consent management platform or other consent interface must capture the decision, persist it and send the correct updates on later pages. The implementation must also match the site’s legal and policy requirements.
How should organisations manage cookies in 2026/2027?
Cookie compliance is an ongoing control, not a one-time banner project. A workable programme should:
- Discover.Scan every site and app for cookies, pixels, SDKs and tags, then keep the inventory current.
- Classify. Record the provider, purpose, data use, recipients, duration and legal treatment of each technology.
- Apply regional rules. Show the right choices for the visitor’s jurisdiction and do not assume the UK exceptions apply elsewhere.
- Enforce. Prevent non-essential technologies from loading until a valid choice exists, where consent is required.
- Make choice clear. Use understandable categories, balanced controls and an easy route back to cookie settings.
- Propagate changes. Update tags and connected systems promptly when a visitor grants, refuses or withdraws consent.
- Keep evidence. Maintain an auditable record of what was shown, what the visitor chose, when they chose it and which notice version applied.
Syrenis provides a cookie consent management platform for global estates that need cookie discovery, jurisdiction-aware consent experiences, pre-consent enforcement and auditable records across multiple properties. Explore the platform or book a demo to see how it works.
Frequently asked questions
What happens if I reject cookies?
The website should not set or read cookies that require consent. Features supported by essential cookies should still work, but personalised content, some embedded media, analytics or advertising may be limited. A visitor should be able to change the choice later.
Can I delete website cookies?
Yes. Browsers let users delete cookies for one site or all sites. Deleting them can sign a user out, empty a basket, remove saved preferences and cause a site to ask for choices again.
Are cookies personal data?
They can be. A cookie value or linked identifier is personal data when it relates to an identifiable person or can be combined with other information to single them out. Even where PECR consent is not required, data protection obligations may still apply.
What is the difference between cookies and cache?
Cookies store small values that help a website remember state or recognise a browser. A browser cache stores copies of files such as images, stylesheets and scripts so pages can load faster. Clearing either can change a site’s behaviour, but they serve different purposes.