A viol is superficially like a violin but it is not the same. Like the violin it is a bowed instrument and has a large resonating body, but it has more strings than a violin, the finger board is fretted and the tuning is more akin to a guitar.
It can be used to accompany voices (as it will be in the concert). It works well in mixed ensembles and of course sounds great when several are played together in consort. It suited both the domestic needs and court needs in Tudor England. This may explain why so much great music was written for the instrument in this period. We will hear some of the music in the concert.