The Basic Knit Bind off (or Cast off) is the most common way to finish a project and get it off your needles.
Step 1: Knit two stitches as normal.
Step 2: Slip the first stitch over the second stitch.
Step 3: Knit one.
Step 4: Slip stitch over the new stitch.
Rep this until you have one stitch on your needle.
When you have one stitch left, break (or cut) your yarn and pull tight.
Example of the Basic Knit Bind Off