If everyone could have everything they wanted whenever they wanted, there would be no such thing as politics. Whatever the precise meaning of the complex activity known as politics might be—and, as this book illustrates, it has been understood in many different ways—it is clear that human experience never provides us with everything we want. Instead, we have to compete, struggle, compromise, and sometimes fight for things. In so doing, we develop a language to explain and justify our claims and to challenge, contradict, or answer the claims of others. This might be a language of interests, whether of individuals or groups, or it might be a language of values, such as rights and liberties or fair shares and justice. But central to the activity of politics, from its very beginnings, is the development of political ideas and concepts. These ideas help us to make our claims and to defend our interests.