There has been rapid growth in the number of providers of satellite navigation signals during the past 7 years or so. The providers now are the USA (GPS), Russian Federation (Glonass), European Union (Galileo), China (Beidou), Japan (QZSS), India (IRNSS, GINS). In addition to these primary navigation signals, there are also available a (growing) number of Space-based Augmentation Systems (SBAS) including WAAS, EGNOS, SDCM, MSAS and others. The presentation provides insight into the reasons for this growth, the satellite orbits chosen and the signals available from each. Innovation in the signal structure has encouraged considerations of greater accuracy, partly from the satellite position and clock accuracy, partly from orbit description and modelling and partly from the signal processing techniques in use. Which signals should be used and why? Perhaps, all should be used but this implies increase in receiver complexity. Is it worth it? The presentation will touch upon these critical questions for both the user and receiver designer.