Tefillin
The Shema also commands us to bind the words to our hands and between our eyes. We do this by "laying tefillin," that is, by binding to our arms and foreheads leather pouches containing scrolls of Torah passages.
The word "tefillin" is usually translated "phylacteries," although I don't much care for that term, partly because it isn't very enlightening if you don't already know what tefillin are, and partly because it means "amulet," and suggests that tefillin are some kind of protective charm, which they clearly are not. On the contrary, the word "tefillin" is etymologically related to the word "tefilah" (prayer) and the root Pe-Lamed-Lamed (judgment).
Like the mezuzah, tefillin are meant to remind us of G-d's mitzvot. At weekday morning services, one case is tied to the arm, with the scrolls at the biceps and leather straps extending down the arm to the hand, then another case is tied to the head, with the case on the forehead and the straps hanging down over the shoulders. Appropriate blessings are recited during this process. The tefillin are removed at the conclusion of the morning services. See a general outline of this process and its blessings at Tallit and Tefillin.
Like the scrolls in a mezuzah, the scrolls in tefillin must be hand-written in a special style of writing. A good, valid set of tefillin can cost a few hundred dollars, but if properly cared for they can last for a lifetime.
For more information about tefillin or to purchase valid tefillin online, visit the S.T.A.M. website.