The "Coptic period" is an informal designation for Late Roman Egypt (3rd−4th centuries) and Byzantine Egypt (4th−7th centuries). This era was defined by the religious shifts in Egyptian culture to Coptic Christianity from Roman religion, until the Muslim conquest of Egypt in the 7th century.
The period began in about the 3rd century and, depending on sources and usage, lasted until around the noticeable decline of Christianity in Egypt in the 9th century, or to the arrival of Islam in the 7th century.
Although the term "Coptic period" is utilized in popular discourse, its use in academia is generally avoided due to its imprecise nature, whereas "Late Antiquity" or "Byzantine Egypt" can be defined on chronological grounds.
Coptic Christianity still has many followers in present-day Egypt.