Do apps left signed in use Data Plan MB?

[Ramz]

I have the sony Xperia s.. i was wondering wether leaving apps such as ebay/amazon/fb signed in use data from my 500mb even when i am not roaming them?

i know wifi doesn't use my data plan but when i leave home and wifi is no longer available then i get worried that i might eventually go over 500mb and get charged for things such as signed in apps?

would appreciate some help, Thank You

[girlborofan]

Lots of people think that phones only use the internet when people ask them to, such as actively checking emails, Facebook statuses, etc. This is not true. All apps that are signed in use your mb if you are not on wi-fi. This includes apps such as Facebook, emails, chat apps (eg Google chat, Facebook chat, etc). They are constantly "polling" - checking the internet for notifications, such as new messages, etc. This polling uses your data all the time. It is only tiny amounts used each time they check, but these little bits soon add up; eating through your data allowance.