When you hear "spanking", you probably think of it in terms of punishment. Spankings can actually be more than that: punishment, funishment, and therapeutic. And while the act of spankings may be the same between punishment, funishment, and the therapeutic, they are actually quite different and give off a different atmosphere for the spankee.
As a sub, when you receive a punishment spanking, you know for sure that it's a punishment. There is no leeway or play to it. It's not about making your bum red, but more about teaching a lesson and hoping that you won't make the same mistake. I can say from experience, that my punishment spankings are far more painful and the amount is much harder. Because I'm in a long distance relationship, my spankings are done by me with a brush while Skyping. Daddy has a rule that if he can't hear the sound of the brush hitting my skin, I have to redo that number. I'm also not supposed to squirm too much or make a fuss or that will increase the amount even more.
I won't go too much into a general punishment explanation because I'll probably make another post to explain that. Punishment normally contains three parts to it: the lecture, the punishment, and the aftercare. Not everyone may engage in all three but I think each have importance. The punishment act without the lecture defeats the purpose because the sub won't know what she did wrong. As a Dom/Domme, You should explain to Your sub what they did wrong and why it was wrong in your eyes. The punishment act, in this case spankings, should come after the lecture and should be to teach a lesson such as, "if you do this, you will receive x many spankings." Remember to be strict but fair, that means that You calm down and think out the appropriate spanking amount based on the severity of the act. You want to make a point but You do not want to come off as abusive or use fear as a tactic to make Your sub obey. And lastly, the aftercare; you normally hear this after rough play sessions and how important it is and it's not different during a punishment session. After Your sub has been told what they did wrong and spanked, sometimes they could be shaken up from either the pain or feeling guilty. This is Your time to explain to Your sub that you love them but that what she did disappointed You. You should also remind them not to dwell on the issue and to let it go; the punishment was to make Your sub realize what she did wrong, but now that it's over, it's time to let it go. Give Your sub cuddles and/or kisses. Let her know that everything's okay now.
Funishment is different and it's common among masochistic subs. Depending how well you or Your sub deals with pain, the amount and intensity varies; this is something both parties need to discuss. Funishment differs from punishment because, obviously, nothing wrong was done; it's simply for fun. My funishment spankings are not strict, I don't have to redo them if I don't hit hard enough (but I will anyways) and Daddy and I will agree on an amount. It makes both of us smile.
Therapeutic spankings is something that a lot people don't realize exists or comprehend it. Some people do pay for such spankings, even vanilla people. Just check out this site. There is some science behind it (or psuedoscience depending on what you believe in):
"This supports recent research suggesting that spanking can be an effective tool in relieving anxiety and working with depression. This effect may be caused by the physical release of dopamine and endorphins into the system during and after a spanking. These neurotransmitters stimulate the pleasure centers of our brains and can make us feel very happy and satisfied. "With that being said, this certainly does not mean to spank Your sub every time they're stressed or upset about something. People deal with these things differently and sometime need time for themselves to destress. But the concept is like funishment but with aftercare. The idea is for Your sub to be able to let go for a bit and focus on a fun session with You. In a way, it's almost like letting Your sub exchange the emotional pain for physical pain.
Spankings have many uses and if You and Your sub (or you and your Dom) are curious or interested, it doesn't hurt (much) to check out funishment and therapeutic spankings. I would recommend starting off using Your hand if You're a first timer so You can control how much pain You're inflicting. Once You're comfortable with the the varying strength of Your hit, You're welcome to switch to a brush, paddle, or even a crop. Remember to keep the happiness and safety of Your sub in mind.