a Cookie vs a Session: Difference and Comparison

In PHP, the chosen data of the user, which can be used on multiple sites, can get stored in both session and cookie. Numerous websites use cookies and sessions to save the information of a user across various pages of the website.

Cookies and sessions are both important as they record the data provided by the user for different reasons. To know what’s best for you, knowing the difference between these two is important.

Key Takeaways

  1. Cookies store data on the user’s browser, whereas sessions store data on the server.
  2. Cookies can track user activity across multiple sessions, while session data expires when the session ends.
  3. Cookies are less secure due to client-side storage, while sessions offer greater security with server-side storage.

The difference between a cookie and a Session is that a cookie is saved on the user or client’s side, whereas a session is saved on the server’s side. The web servers send cookies to their client which is in the form of small text or information, whereas sessions are briefly used to store the data, which are further used in various sites.

A Cookie vs A Session

A cookie is a small form of information stored on the user’s PC, reserved with 4KB as the maximum size. It helps the websites to be informed about the users’ activities and browsing history when they open their websites.

Cookies can only store the ‘String’ type of data.

Sessions are used to momentarily preserve the user’s data on the server, which can be used on multiple sites. Sessions are the total time that has been used to perform an activity.

The user’s session begins when he logs in to the application, finishes when he logs out and is stored in binary form.

Parameters of ComparisonCookieSession
DefinitionCookies are text files that are stored on the user’s computer.Sessions store the data of the user for further usage purposes.
SecurityCookies are not safe as they can be accessed and tampered with easily.Sessions have good security factors as the data is stored in encryption.
VariablesTo obtain the data from the cookies in PHP, the global variable $_COOKIE is used.When a user leaves or logs out from the website, the session ends.
StorageCookies can store up to 4KB of data..Sessions of the browser can store up to 128 MB of data.
ExpiryThe user sets the lifetime of a cookie for it to end.When a user leaves or logs out  from the website, the session ends.

Cookies are small files containing text, which is stored in the user’s computer. The size of a cookie can be up to 4KB maximum. HTTP cookies, web cookies, and internet cookies are the other names of cookies.

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Every time a user logs into some application or website for the first time, that particular site sends a bunch of information in cookie form to the user’s computer.

These cookies keep track of all the activities and browsing when the user opens a site. The data is stored in string type. The data collected in cookies is not considered safe as the data is stored in texts, which are easily accessible.

The users get to enable or disable the cookies whenever they want. A user who generates a cookie is the one who can view that cookie and no one else.

Using an HTTP header, cookies are made and shared among the server and browser. The browser decides where the cookies are saved, as Internet Explorer saves them in the Temporal Internet File Folder.

When we search and play some songs on YouTube, the cookies read the data and show the same songs or similar recommendations the next time YouTube opens.

What is a Session?

Sessions are used to briefly store the server’s data for use on numerous sites.

In simple terms, sessions are the time users do an activity, and the time starts when the user opens any website or application and ends when he closes that site or shuts down the computer.

While surfing through the applications on the internet, the web server does not identify the user as the HTTP protocol does not maintain the state.

The data given by the user on the home page or any other application page will not get relocated to other pages. Sessions are used to remove this limitation.

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The user’s data can be stored in session variables, which can be any type. The data stored through session variables are in binary forms or encryptions at the server, making the data safe from the third party.

The session value gets disconnected mechanically when the person using the application shuts down the PC or logs out from that application. For the session values to get stored permanently, they are needed to be stored in the database.

Every session is different for every user, and many sessions can be used in a single application as there are no restrictions.

With the help of a session, a user is identified, and a unique number is saved as a cookie, form field, or URL in the server.

  1. Cookies are not dependent on sessions, whereas sessions are dependent on cookies.
  2. A cookie has a maximum storage of 4KB, whereas a session can store data up to 128 MB in single-use.
  3. A cookie ends at a specific time set for expiring, whereas a session expires when the user closes the application.
  4. In PHP, an expiration date is set beforehand for deleting the data from a cookie, whereas for deleting data from sessions, the session_destroy() function is used.
  5. The data stored in cookies is not secured as it’s in the text, which can be easily tampered with, whereas the data stored in sessions are binary, which only the user can access.
  1. https://ieeexplore.ieee.org/abstract/document/8392612/
  2. https://link.springer.com/chapter/10.1007/978-1-4842-3489-1_8

Last Updated : 11 June, 2023

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7 thoughts on “a Cookie vs a Session: Difference and Comparison”

  1. This is a very informative piece that explains the differences between cookies and sessions with great detail. It also goes into great depth about how each of these data storing methods work.

  2. There seems to be a typo in the comparison table—’Cookies can store up to 4KB of data..’ Instead, it should be ‘Cookies can store up to 4KB of data.’ Other than this, the article is very informative.

    • I believe it’s actually correct as it is. The ellipsis at the end of the sentence indicates that there’s more to read, so it should be kept as is.

  3. Great article, but the information may be a bit too technical for beginners. Maybe some briefly explained examples could be added to make it easier to digest.

  4. The article provides an excellent comparison of cookies and sessions, explaining the differences between the two and their respective uses in PHP. The session_destroy() and session.cookie_lifetime parameters are particularly important to note.

  5. I found the comparison table to be particularly helpful as it provides a clear and concise overview of the key differences between cookies and sessions. The article does a great job of highlighting their importance in data storage.

  6. This article provided an in-depth explanation of cookies and sessions in PHP. I appreciate that it included key takeaways and a comparison table which made it easier to understand the differences.


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