Bitwise OR (|)

The OR operator (|) compares two numbers bit by bit. For each position, the result has a 1 if at least one input bit is 1. Only when both are 0 does the result have a 0.

Example: $12 | 10$. In binary, $12 = 1100$ and $10 = 1010$. Comparing: $1|1=1$, $1|0=1$, $0|1=1$, $0|0=0$. Result: $1110 = 14$.

OR is how you set bits. If you want to make sure bit 3 is turned on, you OR the number with $2^3 = 8$.