Shedim are demons. People in the circles I move in dont really believe in them except as figures of speech. You might say the shedim came and made my chicken soup overboil. (Chasidic sources say shedim are particularly intent on spoiling ones preparations in the last moments before Shabbat. I can well believe it.) In the Bible, shedim means foreign gods (eg Deuteronomy 32:17.) The word is related to the Akkadian sedu, meaning demon. Its tempting to speculate whether theres any connection with the Old English shade, meaning spirit, which derives from the Greek skotos, meaning darkness. In the past, many Jews did believe in shedim. The Babylonian Talmud refers to them, probably under the influence of the local culture which knew of a profusion of demons. Rabbi Yochanan Ben Zakkai mastered every important branch of knowledge, and in addition understood the speech of shedim (Succah 28a). Shedim live in deserts, dirty places or ruins. They are particularly fond of privies. One needs to watch out for them especially around uncovered food or water. This suggests that shedim may have been an explanation for the observed health dangers accompanying these phenomena. Belief in shedim persisted well into the Middle Ages. The great rationalist philosopher Maimonides had no truck with them and began the process of booting shedim out of Judaism once and for all.