When i purchase items from shops,the amount comes of my available balance straight away?

if my available balance is updated soon as i make a transaction when i check online,does that mean that is available to spend as long as i dont go overdrawn,i know my current balance wont change till it goes through process,any help appreciated,just gets a bit confusing,thank you|||I'm not sure if you are referring to a check debit card or credit card. Either way, keep a written record of what you spend and subtract each purchase, that is your true balance. Remember with credit cards to factor in your finance charges.