Standard snaps let you snap to mesh and shape objects, as well as to the active grid.
Non-grid snap types, when active, take priority over Grid Points and Grid Lines snaps: if the mouse is equally near a grid point and some other snap type, it will choose the other snap type.
Snaps to grid intersections. This snap type is on by default.
Snaps to any point on a grid line.
Snaps to pivot points of objects.
Snaps to one of the eight corners of an object's bounding box.
Snaps to the perpendicular point on a spline, relative to the previous point.
Snaps to a tangent point on a spline, relative to the previous point.
Snaps to vertices of mesh objects or objects that can be converted to editable meshes. Snaps to segments on splines.
Snaps to the end points of edges on meshes or spline vertices.
Snaps anywhere along edges (visible or invisible) or spline segments.
Snaps to the middle of edges on meshes and spline segments.
Snaps to the center of triangular faces.