Before PETA existed, there were two important things that you could do if you wanted to help animals. You could volunteer at a local animal shelter, or you could donate money to a humane society. While many of these organizations did useful work to bring comfort to animals who are used by humans, they didn't question why we kill animals for their flesh or their skins or why we use them for tests of new product ingredients or for our entertainment.
PETA's founders sought to give caring people something more that they could do and to provide them ways to actively change society. They wanted to promote a healthy vegan diet and show how easy it is to shop cruelty-free. They wanted to protest, loudly and publicly, against cruelty to animals in all its forms, and they wanted to expose what really went on behind the very thick, soundproof walls of animal laboratories.