Menorah or Chanukiyah?
Most people are familiar with the Chanukah menorah's nine branches—one for each night, plus the tall, center branch for the shamash (literally "the attendant"). But have you ever wondered why these menorahs don't look the same as the famous menorah on the Arch of Titus in Rome, or like the one on the official emblem of the State of Israel? Those menorahs, which only have seven branches—three on each side, with one tall, straight branch in the center—are meant to symbolize the burning bush as seen by Moses and described in Exodus. The seven-branched menorah stood in the Holy Temple and was constructed according to laws put forth in the Torah.
But why seven branches in the first place? Well, there are many theories to explain this. The most popular is that the shape is said to be inspired by the moriah, a plant that typically has seven branches, grows in the Middle East, and has been around since the time of Moses.
A second theory suggests that the seven branches represent the seven heavenly bodies known during antiquity: the sun, the moon, Mercury, Venus, Mars, Jupiter and Saturn. The Jewish historian Josephus alludes to this in the Third Book of his Antiquities of the Jews: "...and as to the seven lamps upon the candlesticks, they referred to the course of the planets, of which that is the number..."
Whatever the reason, the seven-branched "original" menorah should not be confused with the nine-branched Chanukah menorah. For this reason, the latter is often called a chanukiyah, a word coined by the wife of Eliezer Ben Yehuda, the man credited with reviving the Hebrew language at the end of the 19th century. It's especially important not to confuse the two if you plan on purchasing a new menorah this Chanukah—not so much for fear of breaking a law in the Torah, but more out of fear of the look on children's faces when they discover they've been short-changed by two days.