It's whatever the seller decides.
The term is useful to sellers who are listing on a site that is not their own national site. For example, many Canadian sellers actually list on eBaydotCOM the American site, rather than on eBaydotCA, the Canadian one.
It is also useful if the seller is not too sure what is the most efficient method of shipping. For example, a seller may use a slightly cheaper but untracked service for a known repeat customer, but go with a tracked one for a new buyer.
Ask the seller. For you, as a buyer, tracking is irrelevant, as it only protects the seller. You want the least expensive shipping which is probably USPS First Class International, which does give the seller Delivery Confirmation and is much cheaper than the Global Shipping Program which is in turn much much cheaper than GSP.
