Neutral citation, e.g.  EWCA Civ 44, is a court-assigned reference number for a judgment in a common law jurisdiction.
A typical neutral citation is composed of a year, jurisdiction and court, and a unique case number. There may also be a court division or list noted.
For example:  EWCA Civ 17
Neutral citation was first introduced in 2001 and has now been adopted more widely. The ICLR (Incorporated Council of Law Reporting) summarises neutral citation here:
Most cases have a traditional or standard mode of citation, e.g.  QB 23, and can be located on the Law Library shelves. Both standard citation and neutral citation can be used to search for a case within our legal databases.