A denomination is a branch or sect of a religion. Judaism has multiple different denominations, and they vary in size over time and region. They tend to form over disagreements over basic theological tenets. So, the schisms that create them tend to be very contentious.
The main split is between denominations that are orthodox and those that are not. This and some other highlights of the differences will be added here in the future. More information about each specific denomination and some of the key organizations will be organized into the Denominations category.
Some of the topics that are areas of contention are denoted by an alert.