Dhimma is an Arab term used in Islam for the status of Christians and Jews in a region overrun by Muslim conquest who were accorded a protected status and allowed to retain his original faith. Communities had limited rights, no political voice, and paid special taxes, but were allowed to regulate their internal affairs. The people involved are called "dhimmi". In the Ottoman Empire the dhimmi paid "cizye," a poll tax. The main religious communities formed self-governing bodies called "millets."
The origins of the dhimma system came in the 7th century "Pact of Umar".
A Bernard Lewis has noted, there were episodes when the non-Muslim minorities endured serious discrimination and repression, such as the Armenian Genocide of 1890-1918. Persecution in the form of forced conversion or expulsion, though not unknown, was rare in the Muslim world. The Jewish and Christian subjects of the Ottoman Empire were reasonably safe as long as they were seen to respect the terms of the dhimma and did not attempt to exceed the status that it assigned to them. This kind of tolerance - enjoined by religion, enforced by law, endorsed by public opinion - worked well for centuries. It collapsed in the 19th centuries as ethnic nationalism broke up the Ottoman Empire.
- Braude, Benjamin, and Bernard Lewis, eds. Christians and Jews in the Ottoman Empire: The Functioning of a Plural Society (1982) online edition