Can I add more fields in user table?

[abhishek]

I am making an sms subscription module in my website.
I have designed the logic.
Before proceeding any further I wanted to inquire, can i add more fields to user table.

Thanks.

[bobster65]

you can add as many fields to any of the tables as you want as well as adding more tables ...

[abhishek]

I am highly thankful.