The expression "i=0" is a simple assignment statement commonly used in programming and mathematics. Here, "i" is a variable that is being set to the value of zero. This means that any time "i" is referenced in the code or equation, it will represent the number zero until it is changed to a different value. In many programming languages, initializing a variable like "i" to zero is a common practice, especially in loops. For example, in a loop that counts from zero to a certain number, starting with "i=0" ensures that the counting begins at the correct point, allowing for accurate iterations and calculations.