Strange requests in my web project

I am developing a website using a simple framework designed by myself. It happens that I am noticing strange requests when I load my homepage. Requests I am NOT doing in my code, like those underlined in red in this image:

May someone tell me where are these things coming from?

Is there a way to avoid this?

This website of mine is hosted in a VPS server I rented. I configured it (Debian 6) myself and there is no reason for these requests there.