If you shop on line with supermarkets or others who store your card details - think again!!
Like many regular posters, I have been using on line shopping for groceries for 2-3 years ....
My card details were stored for ease of use, and the ocado website simply charged my card with no input needed from me....
Then my account got hacked and it's apparently all my problem... They won't cancel a fraudulent order for £2k even though it hasn't been delivered and I have had to cancel my card and will now have the fun of sorting out the mess with my card provider, sorting out all the other stuff that will get messed up by this and being without cards for the next 2 weeks...
Please think about this - delete your card details and don't save them....
And consider switching to companies that verify card details for every transaction....