The links on the other websites are called external link.
You should not have too much external links on your website.
It's very important to use pictures on your website to bring up the main concepts of your website. Search engines understand the pictures by their alt tags.
Other wise this will affects your website negatively.
If there is no alt tag, search engine doesn't understand anything from the image.
Domain is either you or your company's ID in the Internet, when you apply to connect to Internet, they will give you protocol number. Every device connected to Internet has an IP number.
It's crucial to use alt tag and to make sure search engines know what you are talking about.
Code Type : This shows what type of coding was used in the design of your site.
HTML Version : This shows the version od coding you used in the design of your site.