Straight of grain has very little stretch. Cross grain has considerable stretch. You may know about fabric that is bias. Imagine a square of fabric with a line running diagonally from one corner to another. That line is bias.
Most good fabric is straight as manufactured.
We will discuss how to straighten fabric in a later column. Lay the fabric folded as it came from the bolt on the cutting mat with the selvages away from you and the folded edge next to you. Fold the edge that is next to you up even with the selvages. It is important that the edge you fold up remains absolutely even with the selvage so that your cut strips will be straight. This raw left edge will not be even, so we will make it so.