+1.
Lobbying just means asking a legislator to do something. At a basic level, lobbying is part of the process of having a republic with representatives. When you mail your representative about SOPA or some other issue, you are lobbying. If enough people do it, that's a grass roots lobbying effort, and could be successful. That's a good thing. It's how the system is supposed to work.
Of course, some people have more influence than others. When you, as an individual, mail your representative and say "this bill is bad for the computer business", the representative is probably not going to pay that much attention. If a major business person who lives in the representative's district/state -- say, Bill Gates calls Senator Murray -- the business person is much more likely to be listened to.
Another common type of lobbying is the professional. Various organizations hire lawyer specialists, former politicians/staffers, and other folks whose job it is to figure out how to get access to legislators or their staff and buttonhole them on the sponsoring company's issues. It's awfully hard to legally distinguish between private citizen lobbying and paid lobbyists. And it's not clear that paid lobbyists are that much of an abuse of the system.
The problem here is that lobbyists -- both paid and private -- can attempt to bribe politicians and staffers in various (legal) ways. These can vary from picking up the lunch tab to donations, and often is equivalent to bribery. But lobbying by itself is not inherently bribery.