In html .., what are the 'tags' or 'attributes' that I should care about to improve the visibility of my site in search engines?

Question

For example, the "alt" attribute in the image allows search engines to read the alternate name of the image, also for programs for the blind ....

Answer 1

Yes as said by kiarash Yavari u have to add some meta tags like the <meta name="description" content="BLAH BLAH"/> , <meta charset="UTF-8">
<meta name="description" content="Free Web tutorials">
<meta name="keywords" content="HTML, CSS, JavaScript">
<meta name="author" content="John Doe">, and for making it responsive -
<meta name="viewport" content="width=device-width, initial-scale=1.0">, etc.

Answer 2

There ara some meta tags in html which help google smart crawler to grouping your website and improve the seo. You should search 'website meta tags' for more information.