A mezuzah is a small box that is placed on the right doorpost of Jewish homes.
Inside the box is a parchment scroll with verses from the Torah inscribed on it, including the Shema prayer.
Some people believe that the mezuzah provides special protection over the residents of the home where it hangs, and when they pass by a mezuzah have the custom of kissing it (usually touching the mezuzah with their hand, then kissing their hand).
This contemporary fluted mezuzah from the Jacob Rosenthal Collection is available in silver, gold and imitation wood and comes with double-sided tape for ease of application.