graphic converter/converting jpeg to tiff

[Maria Paulia Belgado]

I was checking out all the stuff that came with mac os x and i found 
something called "graphic converter". Is this a photo editing software? 
Is there some sort of manual out there I can read?

Actually, I am just interested in a way to easily change my jpeg pics 
into tiff. Is there a way to do this quickly without buying or 
downloading software? If not, is there a good software out there that 
can quickly convert dozens of pictures from jpeg to tiff at a time?

thanks