For any religious practice to be accepted and implemented, it has to be tailored to suit the temperament of the times. Therefore, in every yuga or age, the Supreme Lord manifests Himself and descends upon the earth as the yuga-avatara to establish a suitable form of worship and lead humanity on to the path of devotion and righteousness.
krsna-varnam tvisakrsnam sangopangastra-parsadam
yajnaih sankirtana-prayair yajanti hi su-medhasah
This translates to: "In the Kali yuga, intelligent people perform congregational chanting to worship the incarnation of Godhead who constantly sings the holy name of Krishna. Although His complexion is not blackish, He is Krishna Himself."
Born on a Phalguni Purnima in 1486 in Sridhama Mayapura, Bengal, Lord Sri Chaitanya Mahaprabhu is the incarnation of Lord Sri Krishna. Sri Chaitanya took sanyasa at the young age of 24, and then spent the next 24 years spreading the message of Lord Krishna, who he reckoned as the Supreme Personality of Godhead - who must be universally worshipped. Sri Chaitanya Mahaprabhu lived in Puri for the most of his time on earth and spent about 6 years travelling across all of southern India, propagating the message of Lord Krishna. At the human age of 48, in 1534, Sri Chaitanya Mahaprabhu ascended to his heavenly abode, while at Puri.
In Kali yuga, most people don't seem to find the time or inclination to meditate or practice their religious beliefs, and their minds are constantly distracted. They require the strongest of remedies to reengineer their minds and help it focus. While so, unless the remedy offers a pleasant experience and is an easy one to implement, people refuse to accept it. Recognising this, Lord Chaitanya propagated the 'omnipotent Holy Name'. So no matter who the person or what the state of mind, chanting the Hare Krishna malia - mantra comes effortlessly. Chanting the holy mantra can at once diminish negative thoughts, offer transcendental bliss, and deliver a significant spiritual impact. Srimad-Bhagavadam asserts that Lord Chaitanya will propagate sankirtana or 'chanting the name of God' as the practice for worship in Kali yuga.
Sri Chaitanya-charitamrita by Krishnadasa Kaviraja Cosvami - a classic of Bengali literature - recounts the life and teachings of Sri Chaitanya Mahaprabhu.