They fall under visual communication, they are useful for the following purposes:
I. In factories where most of the workers are illiterate, posters are used to educate them in performing their job efficiently. With the help of posters, they are taught how to operate machines and how to make for their safety.
II. On roads, posters are used to g
ive road sings and traffic signals as well as to suggest the buzzards of irregular and rash driving.
III. Posters have become a very effective means of advertising. Small posters with brief but effective story can often be seen inside banks, on the railway platforms and waiting halls, in the lounge of cinema halls etc. large hoardings are displayed almost everywhere on the roadside.