What is the title of Einstein's 1916 book explaining relativity to the public?

Einstein's 1916 book explaining relativity to general readers is Relativity: The Special and the General Theory.

The original German title was Über die spezielle und die allgemeine Relativitätstheorie (gemeinverständlich), meaning “On the Special and General Theory of Relativity: A Popular Account.” Einstein wrote it to present both theories without requiring readers to master advanced mathematics.

The book first discusses special relativity, including the constancy of light's speed, time dilation, and the relativity of simultaneity. It then explains general relativity, where gravity is understood through the curvature of spacetime, before applying the theory to cosmology.

The title is sometimes confused with The Meaning of Relativity, but that is a different work: it originated from Einstein's 1921 Princeton lectures and is more technical. The 1916 book became especially influential after observations of the 1919 solar eclipse supported its prediction that starlight would bend near the Sun.