How to Encode a web address

data:text/html;base64,77u/data:text/html;base64,77u/PCFET0NUWVBFIGh0bWw+CjxodG1sIGxhbmc9ImVuLVVTIiBjbGFzcz0ia

I saw a url as the one above. what is it called. and how do i encrypt a url to be like that.