Up to isometry, the anti de Sitter spacetime of dimension is the pseudo-Riemannian manifold whose underlying manifold is the submanifold of the Cartesian space that solves the equation
and equipped with the metric induced from the ambient metric
where denote the canonical coordinates on a Cartesian space.
(…)
Asymptotically ant-de Sitter spaces play a central role in the realization of the holographic principle by AdS/CFT correspondence.
Ingemar Bengtsson, Anti-de Sitter space lecture notes (pdf)
C. Frances, The conformal boundary of anti-de Sitter space-times, in AdS/CFT correspondence: Einstein metrics and their conformal boundaries , 205–216, IRMA Lect. Math. Theor. Phys., 8, Eur. Math. Soc., Zürich, 2005 (pdf)
Gary Gibbons, Anti-de-Sitter spacetime and its uses (arXiv:1110.1206)
Wikipedia (English): anti de Sitter space