A bye is a run credited to the team's total when the wicket-keeper fails to gather the ball behind the stumps during the course of bowling.
As a consequence of the wicket-keeper's failure, the batsmen can cross over for a run or two, or even more, depending on the circumstance.
The resultant run/ runs is accounted for as extra/ extras and does not accrue in the bowlers or batsmen's account. However it accounts for a negative perspective against the wicket-keeper.
If the ball runs all the way to the boundary then four byes shall be credited to the extras column. The umpire shall signal for byes by raising one arm towards the sky.