why does my car drive in every gear including reverse.

Ummm…Is that a problem?

Would you prefer that it not operate “in every gear including reverse”?

If that is the case, you might want to drain the transmission fluid, as that would pretty well keep you from being able to drive in any gear.

I’m not sure what you want to know. Give us moe information. Are you asking how a transmission works?

I’m guessing from your very vauge post that no matter what position you put the shifter in, your transmission stays in drive. If this is the case, it is a linkage problem and if you post your year, make and model we may be able to give you more detailed advice.