Activity when away

[#1]

I have read some of the similar threads here, and like some other posters I have reached my limit early on in the month.  When I check my settings there is a padlock, which I am assuming means that the site is secure but every night after midnight approx 67 KBs are used ( 99% of the time I am asleep by 2300!) and there has been usage when I am away for the weekend.  how can this be?  I cannot check with daily usage of previous months as the records don't go back that far, but i have never had a problem previously.  Any thoughts?

[#2]

welcome to the forums
67KBs is very, very little usage. it's generally just background noise. also don't forget that everything after midnight and before 8am doesn't count towards your usage.
If you switch your router off overnight then you wouldn't see this usage.

[#3]

Indeed this is a small amount of data and typical of your modem/router being on.
Whilst considered background noise to most, this can be split down into two areas.
Administrative data, used for things like updating the clock on your computer, keep-alive data to ensure your connection remains up, email notification software and system updates.
True background data, which consists of badly configured software (not always by yourself, sometimes by the software designers), connection attempts from software you may have been running within the recent few hours, badly configured machines/software in neighbouring internet address space causing random data to be sent your way, and finally malicious attempts to connect to you/system probes looking for weaknesses to utilise.
Using some random figures from around the net, this equates to a little under 12500 words of average length, or a small paperback book of between 25 to 40 pages long. Or a even quicker test, barely over one page view of the BBC News website.