# PHP Sessions vs Cookies

While both Sessions and Cookies are used to store data across different pages, they serve different purposes and operate in different ways.

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## 1. Key Differences

| Feature | Cookies | Sessions |
| :--- | :--- | :--- |
| **Storage Location** | Client-side (Browser) | Server-side |
| **Security** | Less Secure (Can be manipulated by user) | More Secure (Stored on server) |
| **Capacity** | Limited (approx. 4KB) | Unlimited (Depends on server storage) |
| **Expiration** | Set by developer (can persist for years) | Ends when browser closes (default) |
| **Data Type** | Strings only | Any data type (Arrays, Objects, etc.) |

## 2. When to use Cookies
*   **Remembering User Preferences:** Theme selection (Light/Dark mode), language settings.
*   **Tracking:** Analytics, ad tracking.
*   **"Remember Me":** Storing a login token (encrypted) to keep a user logged in after closing the browser.

## 3. When to use Sessions
*   **Sensitive Data:** User ID, account details, permissions.
*   **Temporary Data:** Shopping cart items, form data across multi-step forms.
*   **Authentication:** Verifying if a user is currently logged in.

## 4. How they work together
Often, a **Session ID** is stored in a **Cookie** on the user's browser (usually named `PHPSESSID`). When the browser sends a request, it sends this ID, and PHP uses it to locate the corresponding session data on the server.

[[programming/php/php]] [[programming/php/php-cookies-sessions]]