The Torah mandates that a man should wear fringes on the corners of a four-cornered garment.

It is accepted in the Talmud that there is no requirement on a man to actually wear a four-cornered garment, and therefore it is easy enough to avoid having to wear tzitzit at all.

The conclusion of the Talmud is that while this is so, G-d watches over those who wear tzitzit, and that those who wear them are reminded of G-d and the obigations in the Torah when they wear them.

The garment here is in olive drab, for use by Israeli soldiers.