What is latex paint made out of?

Latex paint composition varies somewhat from source to source. However, there are some common parts:

~40% water

~20% vinyl acetate/vinyl acrylic or vinyl acrylic polymer (in emulsion)

Surfactant (soap)

Opacity agent (titanium dioxide primarily)

Rheological modifier (to provide easy application)

Anti-microbial agent (BIT or CIT)

and Pigment