Does Wi-Fi Count Towards Data Usage?

[Anonymous]

I've just upgraded my phone and, as they no longer do unlimited internet tarriffs, have had to change that too.
The advisor said that if my net usage on my new phone gets near the limit, or I feel I'm using it too much, then switch to Wi-Fi. Does Wi-Fi not count to your data usage?
Also, I've got 1GB of data usage, so how much of it am I likely to use in a month? It's difficult going from unlimited to having a limit. They said my current average is just over 100MB per month, but that's only because I don't view streaming videos or download anything on it.
Any help and advice would be great as, I'm not completely ignorant about technology, but I do need a bit of help with understanding some things.
Cheers in advance.

[adamtemp64]

No wifi is treated separately from your data allowance

[Anonymous]

But in what way different?
For example: What happens if I've got a week left until the end of the month and I've used 950MB? Do I just not access the internet until the next month, or is it free to use Wi-Fi in a place with Wi-Fi access?

[adamtemp64]

Any of the included wifi is free all month when you hit your limit your cell data will slow right down but you can still use wifi see these support pages http://tinyurl.com/35g2qaj

You will also be notified via text message in real time.  We’ll send a text message when youve used 80% of your bundle advising you to track your usage via My O2 and reminding you to use Wi-Fi. We’ll send a further text when you’ve used 100% of your bundle asking that you buy more data via My O2 or use Wi-Fi until your next bill date.If you don’t purchase additional data and continue to use the O2 network, your service will be slowed down.

[Anonymous]

That's great.
Thanks for replying and clearing it up for me. I tried to find info about it on the main site, but couldn't find exactly what I needed.
Cheers