Q:

Open cv drawing contours

I have started learning OpenCV and my knowledge of c++ although not poor is not extremely good as well.
While writing a program to find contour i come across 
 vector<vector<Point> > contours;

Can someone please explain me this line?
I understand vector is a template of some sort and the thing inside<..> is supposed to indicate data type stored.
However i'm not very clear as what that line does.
Any help would be much appreciated.
Thanks in advance :)

A:

It's a vector of vector of points. 
Each contour is a vector (sequence) of points. 
Then this is a vector (sequence) of contours.

