Clearly the nature of, and the need for, voter education will vary dramatically from society to society, but when it comes to educating voters on how to fill out their ballot papers, there are identifiable differences between the different systems. The principles behind voting under preferential systems such as AV, STV, or Borda Count are quite complex, and if they are being used for the first time, voter education needs to address this issue, particularly if the voter is obliged to number all candidates in order of preference, as is the case in Australia. The increasing use of mixed systems, many of which give voters two ballot papers, also creates an additional level of complexity for voters. By contrast, the principles behind single-vote systems such as FPTP, PBV, or SNTV are very easy to understand. The remaining systems fall somewhere in between these two extremes.