toward or towards; upstair or upstairs

[u3908235]

How do I know which one to use? toward or towards; upstair or upstairs
Can you give me some examples?
thank you.

[amYankee]

Hi u3908235

As I understand it, the preposition "toward" is used primarily in North America, and "towards" is used mainly in British English. I come from the northeastern part of the US, and I use "toward" and "towards" interchangeably, but I probably use "toward" most often.

The word "upstair" can only be used as an adjective. However, "upstairs" is the word that people almost always use. To me, "upstair" sounds a bit poetic.