Validity of a Schengen Visa

[Seulfille]

If you have a single entry Schengen Visa, how long does it last? Can you use it only on the days you specified your travel? Or if you decide to change the day you fly will it still work?
If I got a single entry visa from the Finnish Embassy for example, for two days, could I instead use it to go to Greece for one week?
Any advice appreciated.

[Buenchico]

If you get a single entry visa, from any Schengen country, it's valid for a stay of up to 90 days within the Schengen area.

You can obtain the visa from country A, enter via country B, travel to countries C, D, E, F, etc and leave the Schengen area from country Z as long as you remain within the Schengen zone throughout your stay and don't stay for more than 90 days.

Chris