I'd like to use a lifeline, Regis

Lifelines.  What exactly are they?  If you're on "Who Wants to Be a Millionaire?" then they are a way of narrowing down the answer using different with help.  If you're drowning, its a flotation device thrown to you by a life guard.  But in knitting, what are they?  

Well the answer is this:  They are lengths of scrap yarn you run through the active loops on your knitting needles using a tapestry needle every 10-20 rows to give you a "safe zone" if you mess up so badly you need to rip your work in progress out, you don't mess up or drop stitches when picking them back up.  It is especially useful if you every try lace work and/or a shawl.  There is a  brand of knitting needles known as "Voldeknits", tho any brand of cheaply made cable needles can be considered "Voldeknits".  They are known for having their cables come unglued from the needles in the middle of a huge project such as shawls, in the process dropping (losing) all the stitches from the needles.  A prime example of where lifelines are useful in knitting.

This is true for any sized project, including socks.  I started a pair of socks for my Dad for Christmas.  I am still only 1" into them, because after starting the pattern did I discover either a) I can't count or b) I messed up the pattern right in the gates.  I think its B, but who's to say it wasn't A... Or both for that matter.  Regardless, I wish I would have used a lifeline after starting the ribbing.  It would have been so much easier to rip out.  I did try and add a lifeline with a tapestry needle, but when it came to ripping out, I was finding out how much I caught the yarn i was pulling out... such a pain in the patoot!

I also wish I had used a lifeline in the shawl I tried to knit, but wound up frogging a week ago so I could use the yarn for a hat instead.  I was knitting along, following the pattern when I discovered I messed the pattern up at some point, and couldn't read my knitting to figure out where it happened.  I had used a complete skein of yarn, and was half way through the shawl.  I wound up setting it down in the middle of the row and leaving it for 2+ months.  Until someone asked for a blue hat.  Thus, it is now becoming a hat.

Yes, lifelines are completely optional in knitting as it is in "WWTBAM", but they can be vital!