When saying kiddush (a blessing), many people use a silver cup or goblet, some use gold or even glass. One can use any cup. I personally own a silver goblet that I treasure (shown in the photograph above). It is only used for kiddush. Reciting kiddush is a mitzvah.
It is a Torah commandment to recite kiddush before the evening meal on Shabbat eve and on Jewish holidays.
For those of you that do not understand the significance of kiddush, why not visit Judaism 101, and read about the Shabbat ritual of kiddush and other traditions regarding Shabbat. The entire kiddush is shown in both Hebrew and English.