Original: There are five branches: to Lewisham in the south, Stratford in the north, Beckton and Woolwich Arsenal in the east, and to Central London, splitting to serve Bank and Tower Gateway.
Simplified: It currently  covers several areas of London, reaching Stratford to the north, south to Lewisham, west to Tower Gateway and Bank in the City of London financial district, and east to Beckton, London City Airport and Woolwich Arsenal.