You likely won't notice, but Tuesday will be a bit longer than normal thanks to something called a Leap Second.
Canada Day will come a little later as the world is set to experience a 61-second minute before midnight.
Timekeepers will adjust high-precision clocks so that they are in sync with the earth's rotation, which is being affected by gravitational forces from the sun and moon.
It's not a change that needs to be made to everyday clocks or computers, eventually computers will make the adjustment for themselves.
The importance comes for timepieces using the frequency of atoms as their "tick-tock mechanism."
Since 1971 there have been 25 instances when a leap second has been added.
