Here are some examples of kirtan friends singing and sharing

Kirtan - a definition

Kirtan is: people coming together in a family-like atmosphere for a music session which gives the result of deep meditation. More specifically, it is the call-and-response singing used in spiritual traditions from India. Also known as kirtan-yoga, kirtan is an integral part of bhakti-yoga which is the yoga of developing pure spiritual love.

Jahnavi Harrison

Jahnavi is a wonderful, sweet kirtan singer.  

Mantra

'Man' refers to the mind, and 'tra' means to liberate. A mantra is said to be a spiritual sound vibration that helps to free the mind from negativity.  Various mantras are sung in kirtan. Om, Hare Krishna Maha-Mantra and Govinda mantras are some of the prominent mantras. 

Kirtan from the
Sikh Tradition

Kirtan is a univesal way of connecting with spirit through sacred sound

Essay on the Maha-Mantra

Written by His Divine Grace A.C. Bhaktivedanta Swami Prabhupada -
this appeared on the cover of the first Hare Krishna L.P. released in 1966

The transcendental vibration established by the chanting of Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare / Hare Rama, Hare Rama, Rama Rama, Hare Hare is the sublime method for reviving our transcendental consciousness. As living spiritual souls, we are all originally Krishna conscious entities, but due to our association with matter from time immemorial, our consciousness is now adulterated by the material atmosphere. The material atmosphere, in which we are now living, is called maya, or illusion. Maya means "that which is not". And what is this illusion? The illusion is that we are all trying to be lords of material nature, while actually we are under the grip of her stringent laws. When a servant artificially tries to imitate the all powerful master, he is said to be in illusion. We are trying to exploit the resources of material nature, but actually we are becoming more and more entangled in her complexities. Therefore, although we are engaged in a hard struggle to conquer nature, we are ever more dependent on her. This illusory struggle against material nature can be stopped at once by revival of our eternal Krishna consciousness.

our one stop shop for secondhand instruments and accessories.
Hare Krishna, Hare Krishna, Krishna Krishna, Hare Hare is the transcendental process for reviving this original, pure consciousness. By chanting this transcendental vibration, we can cleanse away all misgivings within our hearts. The basic principal of all such misgivings is the false consciousness that I am the lord of all I survey. Krishna consciousness is not an artificial imposition on the mind. This consciousness is the original, natural energy of the living entity. When we hear this transcendental vibration, this consciousness is revived. This simplest method of meditation is recommended for this age. By practical experience also, one can perceive that by chanting this maha-mantra, or the Great Chanting for Deliverance, one can at once feel a transcendental ecstasy coming through from the spiritual stratum. In the material concept of life we are busy in the matter of sense gratification, as if we were in the lower, animal stage. A little elevated from this status of sense gratification, one is engaged in mental speculation for the purpose of getting out of the material clutches. A little elevated from this speculative status, when one is intelligent enough, one tries to find out the supreme cause of all causes - within and without. And when one is factually on the plane of spiritual understanding, surpassing the stages of sense, mind and intelligence, he is then on the transcendental plane. This chanting of the Hare Krishna mantra is enacted from the spiritual platform, and thus this sound vibration surpasses all lower strata of consciousness - namely sensual, mental and intellectual. There is no need, therefore, to understand the language of the mantra, nor is there any need for mental speculation, nor any intellectual adjustment for chanting this maha-mantra. It is automatic, from the spiritual platform, and as such, anyone can take part in the chanting without any previous qualification. In a more advanced stage, of course, one is not expected to commit offences on the grounds of spiritual
understanding.