Kīrtanam
Chanting the Holy Names together.
Kirtan means glorifying God together, most often by chanting the Holy Names in call and response. The best known is the mahā-mantra:
Hare Krishna Hare Krishna Krishna Krishna Hare Hare
Hare Rama Hare Rama Rama Rama Hare Hare
The Gaudiya Vaishnava tradition teaches that Krishna is fully present in His Holy Name. That may be why kirtan can feel so full, even before you know why.
After kirtan, many people want to keep the Name with them, understand what they chanted, or meet the people they chanted with. Any of these is a good next step.