Like when you visit the escargot website there is a snail in the tab so what is the code for it?
It uses favicon.
That’s a thing called favicon. Basically lets you use a .ico file as a page icon for browsers that supports (e.g., Chrome, Firefox, IE versions post 6.0).
Never knew I’d have to tell someone that in my entire life. 
actually, Escargot’s FavIcon is /public/favicon.png