Basso continuo performance, its teaching, and practice informs and reflects the wealth of musical styles that characterize Italian music from the end of the sixteenth century to the last decades of the eighteenth century. Basso continuo brought an innovative feature to performance: the capacity to respond to each and every interpretation of a work through improvisation. In the 1700s, practical exercises that rehearse the skills needed for basso continuo performance on keyboard instruments in particular begin to appear. Writings on basso continuo illustrate with what difficulty practice in music was diffused. Very few of the early printed treatises speak of how to realize basso continuo in a practical situation, tending instead to concentrate on describing harmonic principles. There are different types of contemporary written-out accompaniments – none of these can be taken as a thorough and complete testimony to basso continuo realization in any style because it is, by definition, impossible to fully notate an improvisation.