what is the "two second" rule?

The "two second" rule is a rule of thumb in driving to help ensure a safe following distance. Here's how it works:

1. Choose a fixed point ahead such as a sign, tree or overpass.
2. When the vehicle ahead of you passes that fixed point, start counting "one thousand one, one thousand two".
3. If you pass the fixed point before you finish saying "one thousand two", you are following too closely and should increase your distance.
4. The rule is adjusted to at least three seconds in adverse weather conditions or when following larger vehicles.

This rule helps to provide enough time to react and avoid potential accidents.