What is meant by First World second n third world

These are postcolonial terms
here in the video I try my best to explain those postcolonial terms. subscribe my channel for more knowledge

london,colonizers,second world,pakistan,first world,bs english,usa,english literature,third world,uk,english,india,plurality,fourth world,ma english,postcolonialism,hybritidy,literature,colonized,colonization,subject,one hundred years of solitude,