Hello and thanks for your post,  

Yes, it is fairly common practice to take biopsies during a colonoscopy. This is considered to be useful and of benefit, with relatively low risk. 

Biopsies are small tissue samples that seen under a microscope, can provide detailed images of the bowel cells. So, a 'snapshot' of the bowel tissue itself.

This can be used to aid diagnosis of various bowel conditions, and to assess inflammation as well.

Hope that this is helpful,

Best wishes,

Vanda