How are credit cards used safely online? what is the exactly happnes after you give your credit card # online?

I would like to know the exact process, as to what happns with my credit card number, after I use it online? Does a computer code it? Or is my number accessisble to others?

how do I change my visa credit card number?

I have a new Visa card for you to recieve payments. How do I change to the new number?

When getting a visa credit card, after its expiration date do we get a new credit card number?

I want to know whether or not the visa credit card number is valid after the expiration date or a new number is issued and if theold number is valid how the expiration date is changed, I mean for how long the date will be extended? 4 years, 5 years or …

Is it possible to get an online credit card?

I was thinking about doing those sites where it says you can get a free Ipod etc. I’m 99% sure they work, but I am not to keen on giving them my credit card number. For the offers you have to give a credit card for verification, but it’s free. So is this possible?