I'll give you a UK perspective. There was a time when there was a British - US divide in this. In Britain we used the self-effacing 'Don't mention it' and 'Not at all' for a smallish favour and 'My pleasure' for a larger one. 'You're welcome' was an exclusively US response. But times have changed, the traditional phrases are falling out of use, and 'You're welcome' has have crossed the Atlantic to has taken over as the most popular response - doubtless as a result American media dominance. Along with it came many other more casual 'dismissive' responses such as 'No problem' (once an exclusively American expression), 'That's OK' and so on. There's even the Australian import 'No worries', which has become increasingly popular here, especially among younger men. As for the 'Thank you' 'Thank you' exchange, that happens in shops, for example. The shop assistant thanks the customer for handing over the payment, the customer says thank you for handing over the goods, the shop assistant thanks the customer for their custom, while the customer says thank you for the service. So lots of thanking going on there! We're a polite nation.

All of those I have heard used when you do something for someone and they tell you .thank you". With "it's ok" I can't think of anytime which that would be an appropriate response. Usually when you respond "thank you" to someone saying "thank you" its a mutual agreement. For example if you paid for a service. The person saying thank you is saying so because you are paying them but you can say thank you back for the service they performed.

"you're welcome" and "no problem" are the most common replies. for the uses: "thank you for helping me out. i didn't mean to bother you" "not at all." ------------------------------ Don't mention it is a reply for something you're truly grateful for. ------------------------------ "thank you. i even caused you to slip." "no. It's Okay." ------------------------------ "my pleasure" is very formal. ------------------------------

I'm not an english native speaker but my personal experience taught me that the most used response is "You're welcome". At least in movies, TV series and so on.

Philip Broughton-Mil, thank you very much for your explanation. It's very useful.