Joining panels together w/o a seam

I am just working this out in my head so I really don’t have a pattern to go by…

When you knit long panels for a blanket and it is now time to put them together, how do you do this with out making a seam show up on the back of your work?

Thank you for your help

don’t sew!

pick up stitches and do a 3 needle bind off

or crochet them together,

or 'whip stitch (double whip stitch done large, with contrasting yarn will make a series of X’s… which can be decorative.

or recognize there is front/ back and have seams.

Thank you for your help.