I've actually lived in Israel when i was little in a small town that was right next to a kibutz, and I remember going there very often on the weekend. These communities are always clean and quite. the environment is just awsome!!!
As to the official definition, here is something quite accurate:
A kibbutz is an Israeli collective community. Although other countries have had communal enterprises, in no other country have voluntary collective communities played as important a role as the kibbutzim have played in Israel. Its importance can be traced back to the creation of the Israeli state, and continues to the present day.
Combining socialism and Zionism in a form of practical Labor Zionism, the kibbutzim are a unique Israeli experiment, and part of one of the largest communal movements in history. The kibbutzim were founded in a time when independent farming was not practical. Forced by necessity into communal life, and inspired by their own socialist ideology, the kibbutz members developed a pure communal mode of living that attracted interest from the entire world. While the kibbutzim lasted for several generations as utopian communities, most of today's kibbutzim are scarcely different from the capitalist enterprises and regular towns to which the kibbutzim were originally supposed to be alternatives.
The kibbutzim have given Israel a wildly disproportionate share of its military leaders, intellectuals, and politicians. Though the kibbutz movement never accounted for more than 7 % of the Israeli population, it did more to shape the image Israelis have of their country, and the image that foreigners have of Israel, than any other Israeli institution.