S0 a QUARTER STITCH is literally 1/4 of a full stitch - just one of the 4 arms of an X, worked from the corner indicated by the symbol on your pattern, into the centre of the stitch.  Unfortunately, this does not always provide the best coverage.  For example if you have a line of quarter stitches all together, as shown in the graph to the left below (which includes backstitching), they would look similar to the example on the right, when stitched:

As you can see, there's a LOT of fabric showing with this type of stitch.  Now one way to remedy that is to increase the number of strands being used.  More floss equals better coverage, which is one of the reasons I just LOVE using 3 strands of floss (3X) in my designs...  However, if you do a THREE-QUARTER stitch, rather than a quarter stitch, you get the kind of coverage shown below:

Quite a difference isn't there?  Well, let me share the best way to do a 3/4 stitch, LOL, as there is a great 'trick'.  Make a HALF-STITCH in the direction of the 2 diagonal symbols on the graph, then work the quarter stitch from the remaining corner, OVER the half-stitch, into the centre, like this:

The best reason for doing this is that it anchors the stitch, so if you have backstitching, none of the stitching will slip out from under the backstitched edges and blur your outlines.  That's it for this month... happy stitching!