What is a bye in a chess tournament?
In any single elimination pool tournament with an odd number of
players or teams, a by is always neecssary. This is one reason
double elimination can be slightly more "fair", or points are
used.
Players or team are paired, 1 to 1, but with an odd number in
any round, a player has no one to play. This player gets advanced
to the next round as if he/she had a win, and this is called a
"bye". The play should be arranged such that no player or team gets
more than one bye.