ELI5: draw and explain crt

What is a cathode ray tube?

A cathode ray tube (CRT) is like a magic box that shoots tiny invisible bullets of electricity at a glowing screen to make pictures [1][2]. These electron bullets hit the screen and make it light up in different colors, just like how a paintbrush creates pictures on paper [2].

How does it draw the picture?

Inside the CRT, there's an electron gun that shoots electrons one line at a time across the screen, from left to right [3][5]. It draws the picture line-by-line, starting at the top and working down, then starting over again super fast so your eyes see a complete picture [5].

Why do old TVs look different?

CRT screens draw pictures one line at a time with gaps between them, which is why you might notice scan-lines on old CRT TVs [5]. This line-by-line drawing makes CRT pictures look smoother than modern screens even when they're showing fewer images per second [3].

Why don't we use them anymore?

CRT screens take up a lot of space because they need room for all those electrons to travel inside the tube, so newer flat screens replaced them [2].