  In this note, we introduce a new type of warped products called as sequential
warped products to cover a wider variety of exact solutions to Einstein's
equation. First, we study the geometry of sequential warped products and obtain
covariant derivatives, curvature tensor, Ricci curvature and scalar curvature
formulas. Then some important consequences of these formulas are also stated.
We provide characterizations of geodesics and two different types of conformal
vector fields, namely, Killing vector fields and concircular vector fields on
sequential warped product manifolds. Finally, we consider the geometry of two
classes of sequential warped product space-time models which are sequential
generalized Robertson-Walker spacetimes and sequential standard static
spacetimes.
