Vespers, otherwise known as Evening Prayer, is prayer throughout the world in many Churches. It is one small section of the immense Christian Church prayer system known as the Liturgy of the Hours or the Divine Office. Scratch a Christian prayer and you'll find that it originates or has an echo somewhere in this ancient system. Vespers has a very large Christian musical repertoire, that is greatly underrated, and deserves greater exposure and use in Churches and Christian homes.
Some years ago I made a Powerpoint Presentation on Vespers to explain how it is used today in many forms and in most Churches. Of course this is only an introduction - Benedictine sites in particular contain much more detailed information about how Vespers and the other six prayer offices are planned and performed.
Here's the Vespers Presentation link to copy and paste into your URL -
If you find my presentation useful, please use it, with acknowledgement.