  The Einstein Probe (EP) is a mission designed to monitor the sky in the soft
X-ray band. It will perform systematic surveys and characterisation of
high-energy transients and monitoring of variable objects at unprecedented
sensitivity and monitoring cadences. It has a large instantaneous field-of-view
(3,600 sq. deg.), that is realised via the lobster-eye micro-pore X-ray
focusing optics. EP also carries a conventional X-ray focusing telescope with a
larger effective area to perform followup observations and precise positioning
of newly-discovered transients. Alerts for transient objects will be issued
publicly and timely. The scientific goals of EP are concerned with discovering
faint, distant or rare types of high-energy transients and variable sources.
Within the confines of a modest-sized mission, EP will cover a wide range of
scientific topics, from the nearby to high-redshift Universe. The Einstein
Probe is a mission of the Chinese Academy of Sciences, and also an
international collaborative project. This paper presents the background,
scientific objectives, and the mission design including the micro-pore optics
and CMOS technologies adopted, the instruments and their expected performance,
and the mission profile. The development status of the project is also
presented.
