In mathematics, a frame bundle is a principal fiber bundle F ( E ) {\displaystyle F(E)} associated with any vector bundle E {\displaystyle E} . The fiber of F ( E ) {\displaystyle F(E)} over a point x {\displaystyle x} is the set of all ordered bases, or frames, for E x {\displaystyle E_{x}} . The general linear group acts naturally on F ( E ) {\displaystyle F(E)} via a change of basis, giving the frame bundle the structure of a principal G L ( k , R ) {\displaystyle \mathrm {GL} (k,\mathbb {R} )} -bundle (where k is the rank of E {\displaystyle E} ).
The frame bundle of a smooth manifold is the one associated with its tangent bundle. For this reason it is sometimes called the tangent frame bundle.