The term "lobbyist" came into usage early in the 19th century, although stories of its origin vary. One account describes "lobby-agents" as the petitioners in the lobby of the New York State Capitol waiting to address legislators. Another version of the story describes the lobby of the Willard Hotel as the meeting site for both legislators and favor-seekers during the early 1800s. Either way, by 1835 the term had been shortened to "lobbyist" and was in wide usage in the U.S. Capitol.
Simply put, lobbying is advocacy of a point of view, either by groups or individuals. A special interest group is nothing more than an identified group expressing a point of view — be it colleges and universities, churches, charities, public interest or environmental groups, senior citizens’ organisations, even state, local or foreign governments.
One of the most important elements of 'speaking up' is knowing what to say, and just as importantly, when to say it. As Plato said "Wise men speak because they have something to say; fools because they have to say something."
Plato has a lot to say about politics, and if you want to know more about lobbying, Googling to see what he is on the topic is a good place to start. Winston Churchill, too, has said a few things on politics in his time, though admittedly with a little more vigor and arguable with a little less diplomacy than Plato.
Some of this commentary is sourced from the American League of Lobbyists’. It is the preeminent national organisation representing professional lobbyists in the USA.