1 Three-Webs and Geometric Structures Associated with Them.- 1.1 G-Structures, Fibrations and Foliations.- 1.2 Three-Webs on Smooth Manifolds.- 1.3 Geometry of the Tangent Space of a Multidimensional Three-Web.- 1.4 Structure Equations of a Multidimensional Three-Web.- 1.5 Parallelizable and Group Three-Webs.- 1.6 Computation of the Torsion and Curvature Tensors of a Three-Web.- 1.7 The Canonical Chern Connection on a Three-Web.- 1.8 Other Connections Associated with a Three-Web.- 1.9 Subwebs of Multidimensional Three-Webs.- Problems.- Notes.- 2 Algebraic Structures Associated with Three-Webs.- 2.1 Quasigroups and Loops.- 2.2 Configurations in Abstract Three-Webs.- 2.3 Identities in Coordinate Loops and Closure Conditions.- 2.4 Local Differentiable Loops and Their Tangent Algebras.- 2.5 Tangent Algebras of a Multidimensional Three-Web.- 2.6 Canonical Coordinates in a Local Analytic Loop.- 2.7 Algebraic Properties of the Chern Connection.- Problems.- Notes.- 3 Transversally Geodesic and Isoclinic Three-Webs.- 3.1 Transversally Geodesic and Hexagonal Three-Webs.- 3.2 Isoclinic Three-Webs.- 3.3 Grassmann Three-Webs.- 3.4 An Almost Grassmann Structure Associated with a Three-Web. Problems of Grassmannization and Algebraization.- 3.5 Isoclinicly Geodesic Three-Webs. Three-Webs over Algebra.- Problems.- Notes.- 4 The Bol Three-Webs and the Moufang Three-Webs.- 4.1 The Bol Three-Webs.- 4.2 The Isoclinic Bol Three-Webs.- 4.3 The Six-Dimensional Bol Three-Webs.- 4.4 The Moufang Three-Webs.- 4.5 The Moufang Three-Web of Minimal Dimension.- Problems.- Notes.- 5 Closed G-Structures Associated with Three-Webs.- 5.1 Closed G-Structures on a Smooth Manifold.- 5.2 Closed G-Structures Defined by Multidimensional Three-Webs.- 5.3 Four-dimensional Hexagonal Three-Webs.- 5.4 The Closure ofThe G-Structure Defined by a Multidimensional Hexagonal Three-Web.- 5.5 Three-Webs and Identities in Loops.- Problems.- Notes.- 6 Automorphisms of Three-Webs.- 6.1 The Autotopies of Quasigroups and Thl#±