Sorry that we haven't gotten to this post
Technically, you can only be in the Schengen countries for 90 days per 6 month periods.
Guerilla way, we say you can only be in the Schengen countries for 90 days in a row, total. So, if you go out of these 15 countries at any point of your trip, for let's say 3 days you head to the Czech Rep or Hungary, then go back into one of these 15 countries, you'll have another 90 days in a row. So save your receipts from countries that are not in the Schengen for proof that you left.
The name "Schengen" originates from a small town in Luxembourg. In June 1985, seven European Union countries signed a treaty to end internal border checkpoints and controls. More countries have joined the treaty over the past years. At present, there are 15 Schengen countries, all in Europe.
The 15 Schengen countries are: Austria, Belgium, Denmark, Finland, France, Germany, Iceland, Italy, Greece, Luxembourg, Netherlands, Norway, Portugal, Spain and Sweden. All these countries except Norway and Iceland are European Union members. More info on the Schengen Treaty and Countries
I was in Madrid for over a year, so I extended my trip by 10 months without any kind of visa. I came back- no problem. I've heard that even if they find out that you've overstayed illegally, you wouldn't have a problem and they'll just let you be, because of great relationships with Europe and Canada/USA/Australia.
I'm not a legal advisor, but I say, don't even fret about it