Jews have formed a number of important subcommunities throughout their history, though there are generally fewer formally constituted denominations, sects, or other subgroups in Judaism than in most other major traditions. That is quite remarkable, considering the relatively small global population of Jews and the enormous diversity of cultures in which Jews now live. Major differences among Jewish communities appear most frequently in the relative strictness of ritual observance. Variations in theological views are also noteworthy in some cases, but they are less critical. Strictest in observance are Orthodox Jews, with Conservative communities somewhat less strict. Reform Judaism is further removed from the nearly all-inclusive adherence to biblical and traditional practices. And most flexible of all, both doctrinally and ritually, are the Reconstructionists.