One of the most common stitches for hand sewing leather is the saddle stitch. It's essentially a double running stitch. You use two needles, one on either end of your thread. With your thread centered in the first hole, make a running stitch with the needle on the back side.
Hand basting is easier to remove than machine basting, and it is easier to maintain control of an area when you hand baste. Hand basting is sewn with a running stitch. A running stitch is easily removed. Pin the area together as you would sew the area. Thread a hand sewing needle and knot the thread.
Blanket stitch and buttonhole stitch are the same stitch, technically. They are formed exactly the same way. The tailor’s buttonhole stitch is a completely different stitch altogether, as it is formed differently, and in no historical reference do we see “buttonhole stitch” illustrated with an extra knot.
Triple - Three needles on a crossbar so you can stitch 3 rows at once. May be used for machine embroidery and heirloom sewing. Available in size 2.5 mm/80 and 3.0 mm/80. Wing - Needles have side "wings," to create openings in the fabric while stitching. Excellent for heirloom sewing. Available in sizes 2.5 mm/80, 3.0 mm/90, 4.0 mm/100 and 5.0 mm/120.
Chenille needles are sized like tapestry needles, starting at size 14 (which is gargantuan) and progressing up to a size 28, which is extremely fine. So, like any needle, the lower the number, the larger the needle. The higher the number, the finer the needle.