Mesh
The geometry type most 3D models are made of: vertices, edges, and faces.
A mesh is the standard surface representation in Blender and most 3D software. It is built from exactly three components: vertices (points in space), edges (lines connecting two vertices), and faces (the filled surfaces spanning three or more vertices). Everything from a cube to a film-quality character is those three components arranged carefully. In Blender you edit mesh in Edit Mode, entered with Tab.
Related: Vertex · Edge · Face · Edit Mode
These fundamentals are covered hands-on in Blender Geometry Essentials 01, free with a free account.