Other wise this will affects your website negatively.
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.
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.
The links on the other websites are called external link.
That's why you should use alt tag on your all pictures, which you use in your website.
Analytic : Google, along with being the worlds largest search engine also provides many other great services. With a tiny code added to your site, Analytic allows you to track all user data on your site.