History of Nama-hatta
Just over 500 years ago, Shri Caitanya Mahaprabhu, in the Shri Chaitanya Bhagavata, gave the following order to His pioneering preachers Shri Nityananda Prabhu and Shri Haridas Thakura:

suno suno Nityananda, suno Haridasa,
sarvatra amara ajna koroha prakasa,
prati ghare ghare giya koro ei bhiksa,
bolo Krishna, bhaja Krishna, koro Krishna siksa

“O hear Me, hear Me Nityananda! Hear Me Haridasa! Simply disseminate My order everywhere. Go from house to house and beg [the residents as follows]: ‘Speak about Krsna, worship Krsna and teach [others] about Krsna.’”

[Caitanya-bhagavata Madhya-Lila 13.8-9]

Over 100 years ago, the great Acharya Srila Bhaktivinoda Thakura, in the line Gaudiya Vaishnavasim, again took up the preaching mission of the Lord Caitanya and recorded the following words in reference to the Nama-hatta preaching work:

boro sukher khabor gai
surabhi-kunjete namer hat khule’che / khoda nita

“I am singing news of the greatest happiness! At the place known as Surabhi Kunja in Shri Navadvipa, the Marketplace of the Holy Name has now been opened-and Lord Nityananda Himself is the Proprietor.” [Vaisnava-Siddhanta-Mala]

Bhaktivinoda Thakura – the Innovator of the Marketplace
Srila Bhaktivinoda Thakura personally travelled to so many places and established over 500 Nama-hatta sanghas. He organised roles for running the Nama-hatta smoothly. Each Nama-hatta was headed by a commander who took care of the members of the Nama-hatta. He designated the travelling preachers who went from door to door as salesmen. Finally, he considered himself simply as the sweeper whose purpose was to help maintain purity by speaking Harikatha and singing kirtans at the houses he visited.

Nama-hatta in ISKCON
Srila Bhaktivinoda Thakura’s modern-day Nama-hatta mission continued with Srila Prabhupada, the founder of the International Society for Krishna Consciousness (ISKCON), His disciples including HH Jayapataka Swami (Minister for Congregational Preaching), HH Bhakti Raghava Maharaja, HH Bhakti Purushottama Swami, and HH Gauranga Prem Swami have expanded these Nama-hatta by the thousands throughout West Bengal, Bihar, and Orissa. This enthusiasm has rippled out and initiated thousands of more Nama-hattas all over the world.

What do Nama-hattas accomplish?
Provide regular opportunities to associate with devotees even if they live far from temples
Support advancement in spiritual life for householders, even as they are busy with work and family
Serve as expansions of temples to reach out and include all
Connect aspirants to Harinam initiations
Avail welcoming places for those who have received Srila Prabhupada’s books and other various newcomers
Preaching facilities without taking funds from temple collection
Facilitate practice for preachers, including young people and women
The above is taken from https://iskconcongregation.com/programs/creating-markets-of-the-holy-name