Does anyone know of a good basic Media Studies resource for this anon? Preferable one that’s freely available online?

Hi. I’m a “media” student from a third world country but due to the low quality of education many things, as I realized now that I am researching for my undergraduate thesis, weren’t thought to us (all we were though was how to write articles and stuff). With that said I just wanna ask what is a media text? What is the difference when you say media and media text and when should I be using one or the other? I just wanna learn more you see and there so much I still need to know. Thank you.