No priest, neither ordinary priest nor the
High Priest himself,
was fit to serve in the Tabernacle unless he was wearing the
priestly garments.
The lay, or ordinary, priests must wear four
garments - the tunic, the belt, the turban and
the pants.
These garments were made from white flax;
hence they were referred to as the "garments of white,"
and they were also worn by the High Priest on the Day of
Atonement.
More about the priestly garments...