Speaking in tongues is a subject of great interest among Christians, and many do so. However, many of those who do understand that God wants us to speak in tongues have not been sufficiently taught as to why it is so vital. Thus, they do it only sporadically. In contrast, the Apostle Paul, who is set forth as an example of what a Christian can be, wrote to the Church at Corinth that he spoke in tongues more than their entire church put together.
This teaching is primarily for people who already speak in tongues, and is an exhortation to do so as much as possible. It does not teach how to speak in tongues, but goes into detail as to why we should, setting forth the benefits and blessings of utilizing this magnificent manifestation of the spirit.