Sangha is the traditional Buddhist word for “spiritual community” — one of the “three jewels”, along with Buddha (Awakened Being) and Dharma (The Teaching).
Nowadays, sangha also has an interfaith meaning: any group of spiritual friends or contemplatives who meditate together, study spiritual teachings, and support each other on the path. In this sense, practicing together is what makes a group a sangha, no matter how diverse the backgrounds or beliefs of its membership.
There are individual “sanghas” — specific groups, with particular histories, identities, doctrines and norms. You might have to formally join (or at least show up someplace) to become a member of one.
There is also just Sangha — the one Universal Sangha of all who walk the contemplative path. You automatically belong to this Sangha the moment you aspire to the path, or find yourself on it.
A virtual sangha is such a community centered online … or nowhere.