In PHP form handling, what are the main differences between the GET and POST HTTP methods when submitting a form?

Introduction / Context:
In web development with PHP, HTML forms can submit data using different HTTP methods, most commonly GET and POST. Understanding the practical differences between these methods is essential for designing secure and user friendly applications. Interview questions about GET versus POST verify that a candidate knows how data is transmitted, how PHP reads it, and which method is more appropriate for different types of actions.

Given Data / Assumptions:

• HTML forms include a method attribute that can be set to GET or POST.
• PHP exposes GET data through the $_GET superglobal and POST data through the $_POST superglobal.
• URLs have practical length limits enforced by browsers and servers.
• Sensitive data such as passwords should not be exposed in URLs.

Concept / Approach:
GET and POST differ mainly in how data is sent from the browser to the server. With GET, form parameters are appended to the URL as a query string, which is visible in the browser address bar and can be bookmarked or cached. With POST, form data is placed in the request body, which does not appear in the URL and is better for sending larger or more sensitive data. On the PHP side, both methods are accessible and processed similarly, but their semantics and typical use cases differ: GET is generally used for safe, idempotent requests like searches or filters, while POST is used for actions that change server state such as creating new records or submitting forms with files.

Step-by-Step Solution:
Step 1: When a form uses method="GET", the browser constructs a URL like example.php?name=John&age=20 and sends it with minimal or no request body. Step 2: PHP receives this request and populates the $_GET array with key value pairs parsed from the query string. Step 3: Because the query string is part of the URL, it is visible in the browser, may be logged in server logs, and is subject to length limits that make sending very large data impractical. Step 4: When the form uses method="POST", the browser sends the same parameters in the HTTP request body, and PHP populates the $_POST array with them. Step 5: POST requests can carry much larger payloads, especially when combined with enctype="multipart/form-data" for file uploads, and the data does not appear in the URL. Step 6: For these reasons, the main difference is about where data is placed (URL versus body), visibility, typical size limits, and appropriate use cases, which is correctly summarised by option a.

Verification / Alternative check:
You can verify these differences by building two simple forms, one using GET and one using POST, and submitting them to the same PHP script. Inspect the browser address bar and server logs to see that GET parameters are visible in the URL and can be bookmarked, while POST parameters are not. Tools like browser developer panels will show that POST sends data in the request body, confirming the conceptual explanation above.

Why Other Options Are Wrong:
Option b is wrong because neither GET nor POST automatically encrypts data; encryption requires HTTPS at the transport layer. Option c is incorrect because both methods can be used any number of times. Option d is wrong because GET and POST are HTTP protocol concepts and are not tied to any specific server side language; PHP, Python, Java, and others all support them.

Common Pitfalls:
A common pitfall is using GET for actions that change data, which can lead to unexpected repeats when users refresh or share URLs. Another issue is placing sensitive information such as passwords, tokens, or personal data in GET parameters, which can leak through browser history or logs. Best practice is to use GET for safe, read only queries that can be bookmarked and use POST for state changing operations and larger or sensitive payloads, always over HTTPS when security is important.

Final Answer:
GET sends form data as a query string in the URL with visibility and length limits, while POST sends form data in the request body, supports larger amounts of data, and is better suited to sensitive or binary data and operations that change server state.