Advances in technology over the last 25 years have created a situation in which workers in diverse areas of computerscience and engineering have found it neces­ sary to increase their knowledge of related fields in order to make further progress. Clifford (geometric) algebra offers a unified algebraic framework for the direct expression of the geometric ideas underlying the great mathematical theories of linear and multilinear algebra, projective and affine geometries, and differential geometry. Indeed, for many people working in this area, geometric algebra is the natural extension of the real number system to include the concept of direction. The familiar complex numbers of the plane and the quaternions of four dimen­ sions are examples of lower-dimensional geometric algebras. During "The 6th International Conference on Clifford Algebras and their Ap­ plications in Mathematical Physics" held May 20--25, 2002, at Tennessee Tech­ nological University in Cookeville, Tennessee, a Lecture Series on Clifford Ge­ ometric Algebras was presented. Its goal was to to provide beginning graduate students in mathematics and physics and other newcomers to the field with no prior knowledge of Clifford algebras with a birds eye view of Clifford geometric algebras and their applications. The lectures were given by some of the fields most recognized experts. The enthusiastic response of the more than 80 partici­ pants in the Lecture Series, many of whom were graduate students or postdocs, encouraged us to publish the expanded lectures as chapters in book form.