Basting

To baste something means to temporarily attach two pieces of fabric in place so that they will hold their position until a more permanent stitch seals them in place.



Pin-Basting
The most common form of basting is pin-basting, which is such an integral part of sewing that patterns take for granted the fact that you need to pin-baste everything. Pin-basting simply means lining up your fabric, and then using pins to secure the fabric in place for later sewing. Anytime you are going to stitch a seam together, you are expected to pin-baste first.

There are two important parts of pin basting:

1. Orient your fabric to figure out the directions the pins are going in. Sewing machines are set up so that you will be sewing the seam on the right, with the extra fabric on your left, and the fabric will move front-to-back. You want the pins to be put in so that as you're sewing, you can pull the pins out from below as the pin approaches the sewing machine needle. If you have the pins put in so that the head of the pin is at the "top" of the fabric going in, you won't be able to smoothly pull them out as you go. (Note, this is only for it your have the pins parallel with the raw edge as I do, if you do the pins so that they are pointed toward the raw edge, you won't have to worry as much about this).
2. You want the pins to be in at roughly the same place that you will be doing the seam. Don't put your pins in at the edge of the fabric, or too far in, as these will increase the likelihood of the fabric shifting about. Use your seam gauge to measure ⅝"/15mm (or whatever the pattern says is the seam allowance for this stitch) and put your pins in there. You'll get pretty good at eyeballing  ⅝" as you do this.

Baste Stitch
At times a pattern will specifically tell you to baste two or more pieces together using a baste stitch. The elements of thread-basting, again, is that you should be able to remove the seam easily. Sometimes baste stitches remain in permanently, but a baste stitch should always be able to be pulled out without a lot of effort (or even a seam-ripper).

Make sure you double-check the seam allowance (the amount in from the fabric's edge). Since the standard seam allowance is ⅝" (15mm), you might need to do your baste stitch at ⅜". The pattern will indicate if you are going to use a non-standard seam allowance.

Hand-baste

obviously, you will "tighten this down"

Hand-basting is just, as my mom put it, a "long, lazy stitch" with a hand-needle. You don't have to knot your thread at the end, and you just do about a half-inch "up and down" stitch joining the two+ pieces of fabric together in a straight line. Hand-basting isn't used very often, but it's really quite simple. Remember, the point is to keep the fabric "in place" so you don't want your stitches too far apart or it will just separate and slide around. This is why, unless the pattern specifically says to hand-baste, you're going to want to:

Machine-baste
Some machines will have a special "baste-stitch" setting on them, but a baste-stitch is not hard to put together on a machine without that specific setting:

• Start with a straight stitch
• Set the length of the stitch to the longest possible length (usually about a 4-5) 
• Do not fix the start or end of stitch -- if you're using a digital machine, turn off the "fix" option before you start stitching and cut the thread without fixing when you're done, otherwise, if you're using a mechanical machine, just let 'er rip -- don't use the "reverse" button to manually fix your stitch at either end.
• Don't forget when you're done to set your stitch back -- you don't want to use a baste stitch on a permanent seam!

Removing a baste stitch

The purpose of the baste stitch is that it should be easy to remove, without using your seam ripper or snips. Simply grab one of the threads at the end, pinch the other end of the fabric, and pull the thread out. You might experience some bunching of the fabric, this is normal, just smooth out the fabric by pulling it away from the end you're pulling the thread out of, and you'll gradually work the stitch out. You may find with a machine baste, that you need to snip a stitch or two to "get things going" but otherwise, it should be pretty simple to remove.