What is overactive bladder?

From Terry the Pelvic Health Physio again:
If you are going to the toilet more often than your friends and it bothers you, the first thing to do is to work out if it’s your bladder misbehaving or if you’re just drinking way more than you need. Most people only need between 1.5L and 2L of fluid a day depending on how active you are and how hot it is.
Most people will need to pee around 4 to 6 times a day if they are drinking normally and size of each wee will be between 1 and 2 cups.
Assuming you’re not drinking too much; the next question to answer is could this be an infection? If your urine is cloudy, unusually smelly or hurts – you might have an infection. Infections happen when some of the bacteria that belong on our skin or in our gut, make their way into the urethra. If your pee doesn’t flush them out, they get into the bladder or even kidneys and make you very miserable. Infections are quickly and easily treated by visiting your doctor and getting some antibiotics. Your doctor might ask you to pee into a jar to make sure they have given you the right antibiotics for the bugs causing your infection.
So you’re drinking normally and you don’t have an infection! Now what?
Some bladders are overactive, which means they don’t want to fill up properly and won’t relax until you’re ready to go to the toilet. Sometimes it’s the brain that is overactive and it tells the bladder to squeeze every time you open the tap or hear running water. It feels like your bladder is trying to control you instead of the other way round. The more you worry about your bladder the worse it seems to get. Emptying your bladder when it isn’t full can reinforce the pattern and make it worse. Drinking too little concentrates the urine and makes it worse.
So what can you do?
Firstly – try to wait until your bladder is full before emptying it. The only “just in case” pees should be the ones you do before going to sleep or after sex. Drink enough fluid to ensure your urine doesn’t irritate the bladder. Avoid known bladder irritants such as coffee, tea, cola, pepsi, coke etc. Some artificial sweeteners can also irritate the bladder. Practice your pelvic floor muscle exercises – so that you can resist the urge and avoid leaking. Try standing or sitting still until the urge passes to help teach your bladder to relax until you are sitting on the loo.
See your doctor to make 100% sure it’s not an easily treated infection and if you’re still having trouble go see a continence nurse or physiotherapist who can teach your bladder to behave the way you want it to. P.S. there are pills that can help if your problem is very severe, but most people can improve without pills