Have you ever heard of tightlining? Me either but I have heard of lining your upper and lower lash line, however this is a bit more complicated. Basically, you put eye liner whether gel or pencil in between each lash in your lash line. It's a fabulous way to add great definition to your lashes without looking like you're actually wearing a thick layer of liner. It's easy to become a huge fan of this look.
From Beautylish, I found the instructions on how to get this look:
HOW TO Tightline Eyes with Pencil or Gel Eye Liner
1.Using clean fingers, gently lift your lashes upward (this step is only necessary if you find it easier to tightline). You'll see tiny gaps between your lash hairs, which you'll be filling in with eye liner.
2.Using either a gel or pencil eye liner, lightly dab the eye liner in between each individual lash (as close to the root as possible), to fill in your lash line and make it look fuller. Start at the the inner and work to the outer corner of your eye. Congratulations, you've officially tightlined your eyes!
3.To intensify the look, tightline your bottom lash line as well. It's the same concept as the top, but you'll be filling in the space between your lower lashes.