Good afternoon,
I would like the help of the university students, I created a website and put a favicon in the same folder as the pages that call it, but the favicon is not being shown:
<link rel="shortcut icon" type="image/png" href="favicon.ico">
Link: link
Not all browsers are able to recognize favicons. Try using Google Chrome or Mozilla Firefox and make sure they are up to date.
In the case of the site you reported, here I could view without problems using the latest version of Mozilla Firefox. Follow print: 
I know that they have already explained the reason, but just to reinforce, each browser can operate in a different way, so there are TAGS for each one ranging from computers to smartphones. >
I researched and saw that it is necessary to create two files both with 32x32 px being one in ICO format (Converted and not saved by image editors) and another PNG:
<link rel="icon" href="favicon.png" type="image/png" />
<link rel="shortcut icon" href="/favicon.ico" />
To avoid CACHE I advise renaming the files that your browser may not understand at first. There are also the TAGs for several other browsers, especially Smartphones that I will put here if they do not solve your problem.
Use this converter online if you want to generate all necessary formats in an automated way:
(It also generates all tags needed for the header of your HTML)