A public service announcement (PSA) or public service ad, is a message in the public interest disseminated without charge, with the objective of raising awareness, changing public attitudes and behavior towards a social issue. In the UK, they are generally called 'public information films' (PIFs); in Hong Kong, they are known as 'announcements in the public interest' ('APIs').
The earliest public service announcements were made before and during the Second World War years in both the UK and the US.
In the UK, amateur actor Richard Massingham set up Public Relationship Films Ltd in 1938 as a specialist agency for producing short educational films for the public. In the films, he typically played a bumbling character who was slightly more stupid than average, and often explained the message of the film through demonstrating the risks if it was ignored. Films' topics included how to cross the road, how to prevent the spread of diseases, how to swim and how to drive without causing the road to be unsafe for other users. During the war, he was commissioned by the Ministry of Information to produce films for the war effort. Massingham began to produce longer films, for both private companies and the Government, after the War.
In the US, the Ad Council (initially called the War Advertising Council) was set up in 1941, when America entered World War II. It began implementing on a massive scale the idea of using advertising to influence American society on a range of fronts. Their first campaigns focused on the country's needs during World War II, such as encouraging the American public to invest their savings in government bonds.
After the War, PSAs were used to educate the public on a broader range of important issues. In the UK, they were produced for the Central Office of Information (COI), and again by private contractors, which were usually small film companies, such as Richard Taylor Cartoons. They were supplied to broadcasters free of charge for them to use whenever they wished. Their usefulness as a cost-free means to fill the gaps in fixed-duration commercial breaks left by unsold advertising airtime led to their being used regularly and extensively in the 60s, 70s and much of the 80s, and consequently, within both the COI and broadcasting companies they were typically known as "fillers". They are still being produced, although the vastly reduced need for broadcasters to turn to third-party filler material to deal with unused airtime during breaks or junctions means they are now only seen rarely.