Problem with Alt Tag For images

I am using alt tag to optimize images but whenever I see the source of my webpage it is showing the full text that I have used, It's like this

width="250" height="188" alt="GIGABYTE AORUS 15P Best Gaming Laptop Under $2500"

I looked at other sites' sources code but the alt text is not visible.

Am I doing something wrong?

Isn't the alt text is a kind of confidential thing?

The code is something like this that I am using for alt tags.

src="//image.jpg" alt="GIGABYTE AORUS best gaming laptop" width="160" height="120" ></a>

Please anyone help me out with this.