It is difficult to give an exact number of how many religions have existed in human history, as new religions continue to emerge and some have become extinct. Additionally, different sources may classify religions differently and there is also a debate on what constitutes a "religion." But, it is estimated that there are around 4,200 religions in the world today. These religions can be divided into two main categories: Abrahamic religions (Judaism, Christianity, Islam, Baha'i) and non-Abrahamic religions (Hinduism, Buddhism, Chinese traditional religion, Jainism, Sikhism, etc.) Some other religions that have existed in history but not widely practiced or extinct such as ancient Egyptian, Greek, Roman, Norse, and many other indigenous religions.