Answer:
   
   Traditionally, there are halachic rules and community customs that
   lead to a particular pattern of dress for those that observe the
   halacha regarding modesty. This is most typical among the Orthodox
   segment of Judaism, but is occasionally found elsewhere. It is good to
   keep these rules in mind if you visit traditional communities,
   especially in Israel. These dress rules/customs include:
     * Sleeves are typically covered as far as the elbow.
     * The neckline does not expose any cleavage.
     * Skirts are long enough to cover the knee when seated.
     * Depending on the area, pants or slacks may be allowed; for
       example, in many religious kibbutzim the women wear pants out of
       habit, for the simple reason that they work in agricultural areas
       or other activities where a skirt would be less modest. However,
       this is the exception; when not performing these activities,
       skirts are worn. Women not in such situations at all are
       encouraged not to wear pants.
       The problem with pants are two-fold: first, some communities still
       consider them banned under the laws that prohibit cross-dressing.
       The other is that any attire that shows the location of the croch
       is considered immodest attire for women. If the problem is only
       the latter, then perhaps a skirt or apron over pants would be
       permitted. Different rabbis and communities follow different norms
     * Married women cover their hair either completely, or with
       approximately 2 finger widths showing of the bangs. As to
       unmarried women, hair covering is not required, although there are
       Sephardi customs that even unmarried women should "put their hair
       up", so that it's not flying 'wildly' (but not necessary to cover
       it). In some communities, particularly amongst Hassidim and
       Sepharadic Jews (those from Arab countries), wearing a wig is NOT
       sufficient head covering. In some Chassidic groups women wear a
       hat over their wig. Amongst Sepharadic Jews, the wig is of no
       relevance to this law, and the hat would have to be large enough
       to cover all of their hair--making the wig pointless.
       The origin of this law is murky--in one place the Talmud makes
       this seem to be a rabbinically set modesty issue, in another it is
       a scriptural reference. This too is followed by all but the most
       modern edge of Orthdoxy (and even in their camp, most acknowledge
       that they are violating the rule as set forth in the Talmud).