In HTML, what is the marquee tag and what does it do when used in a web page, despite being non standard and deprecated?

Introduction / Context:
The marquee tag is an older HTML construct that was introduced by specific browsers to create scrolling or moving text effects. Although it became popular on early web pages, it has never been part of the official HTML standard and is now considered deprecated. Modern design typically avoids it, but interview questions may still ask about marquee to test knowledge of legacy markup and the evolution of web standards.

Given Data / Assumptions:
The marquee tag is recognized by some browsers but is not part of the formal HTML specification.Content inside a marquee element scrolls or moves automatically in a specified direction.The question asks what the marquee tag does when it is used.We assume awareness that it is deprecated and should be avoided in new projects.

Concept / Approach:
The marquee tag typically wraps text or inline content and applies a scrolling animation, such as moving from right to left, left to right, or bouncing back and forth. It was originally introduced as a proprietary extension and later emulated in other browsers for compatibility. Because it is non standard, behavior can vary and it is not accessible or responsive by design. Current best practice is to use CSS animations or JavaScript for motion effects instead of relying on marquee. However, the core idea remains that marquee makes content move automatically across the screen.

Step-by-Step Solution:
First, recall that marquee is written as a tag that surrounds text, for example marquee Some text marquee.Next, remember that when viewed in supporting browsers, the text inside this tag scrolls across the display area.Then, recognize that the movement can be configured with attributes but that this usage is no longer recommended.After that, review the options and look for the one that mentions a non standard tag causing enclosed content to scroll or move automatically.Finally, confirm that option A matches this description, while the other options talk about video, encryption, layouts, or search engines, which are unrelated.

Verification / Alternative check:
If you create a small HTML file containing the marquee tag and open it in a browser that still supports it, the text inside will scroll continuously. Validation tools, however, will warn that marquee is obsolete or non standard. Official HTML references emphasize that this tag is not part of the standard and should be replaced with CSS or scripted animation. These observations confirm that the main effect of marquee is automatic scrolling of content as described in option A.

Why Other Options Are Wrong:
Option B claims that marquee is a standard tag for video players, which is incorrect because video tags and embedded players are managed through different elements. Option C suggests that marquee encrypts text, which it does not; the text remains visible and simply moves. Option D attributes grid layout capabilities to marquee, but layout grids are usually built with div elements and CSS. Option E states that marquee blocks search engine indexing, which is not its function and not a reliable way to influence search behavior.

Common Pitfalls:
Using marquee for important information can create accessibility issues, as moving text may be hard to read or may distract users. It can also behave inconsistently across devices and is not responsive. Developers should avoid introducing new marquee usage and instead use CSS transitions or animations that can be controlled and paused. However, recognizing marquee code in legacy projects and knowing that it produces scrolling text remains helpful for maintenance and exam questions.

Final Answer:
The correct answer is: It is a non standard tag that causes enclosed text or content to scroll or move automatically across the screen.