Successful currencies meet three criteria:

(1) they are in widespread use as medium of exchange
(2) they serve as unit of account
(3) they are a stable store of value.

Most sovereign currencies fully meet all three criteria.

What ...............,,,,,about Bitcoin?
[lllL/quote]
Bitcoin meets some of these criteria. It can serve as a store of value effectively as well as medium of exchange. But in the aspect of serving as a unit of account, Bitcoin might not fit into that category. It cannot be used as a legal tender.