The terms socialism gets bandied about on these boards a lot. The purpose of this post is to show that, if the term means any one thing at all, then almost everyone here is a socialist.

Let's start off by finding out what every self professed socialist has in common. The thread that runs through socialist thought is that wealth is created in a social context. That means individuals participate in creating wealth, but they do so within the broad framewrok of a whole society. This seems pretty obvious to most people. I mean, no one thinks you can have a pharmacuetical company without doctors or hospitals. And you can't have doctors or hospitals without farmers and factory workers. And so on. So we all accept that wealth is in some sense socially generated. Its a cooperative effort.
Now socialists don't stop there. They say that if wealth is generated in a social context the society has a responsibility to the members of that society invovled in generating that wealth. This basic principle, for example, says you shouldn't enslave people, or have discriminatory laws, because everyone in a society can contribute wealth, so everyone should have rights consistant with that fact. It also means that people shouldn't be forced to work in dangerous conditions or all the hours of the day just to earn enough to live. Since these people are part of the social project of wealth creation, they must be protected by the society that benefits from their labour.
But socialists go even further. They say that there are lots of things people can't do by themselves but that are necessary for that society to function. This includes things that are prohibitively expensive, like maintaining a military, or things that require impartiality, like having a judiciary.
And socialist go even further and point out that economic systems have externalities, and people should be protected from these externalities. If you get injured at work, you should be able to sue, and no one should be able to ask you to give up this right. They say that if you are orphaned, the society should look after you since orphans are an inevitable externality of society. They say that if you become unemployed society should help you get back into work, since unemployment is an inevitable feature of capitalism. This might mean training, it might mean giving you enough to eat. Basic education is a necessity in a society like ours in order for that society to perpetuate itself, so the society should make sure that most people get an education. And so on.

Now notice I haven't mentioned the government once. This is because the government is just one part of society. If society can do everything it needs to do just fine without any government intervention then there's nothing socialistic about interfering. However, according to socialists, it is the role of socialially controlled institutions (in this case our government) to make sure that the society is able to perpetuate itself, and that those who chose to participate in society (by getting an education, working, seeking work, etc.) are protected by society, and allowed to share in the wealth they are helping to create.
So essentially, you are a socialist if you think that society is and should be a cooperative process, and that everyone who is cooperating should be looked after by society.

If you want to object by saying "yes, but socialists do this that and the other, and I don't approve of that", my answer would be twofold. First I would point out you don't have to agree with someone's policy choices to share some of their beliefs or goals. Secondly, and more importantly, I want to argue that socialism is a term that essentially we should stop using. Since the above aspects of thought are all that socialists have in common, its such a braod term that its not terribly useful in political discourse. It's opposite (which would be non-governmental libertarianism) is such a minority position that we should assume 'socialism' to be the default, and only discuss it when contrasting it to this radical form of individualism.