Like a perfect red lipstick I think it is safe to say that we are all on the lookout for a great ,intense long lasting black eyeliner which is often easier said than done.

"Finally a waterproof liquid liner that glides on with ease, won't smudge or run, 
and stays in place until you say when! 
The thin marker-like tip is easy to use even for the least experienced, and delivers a defined thin line to a dramatic bold line with precision. 
Goes on smoothly without skipping, smudging, or pulling, and lasts all day!"

Stila Stay All Day Waterproof Liquid Eye Liner is of course a liquid liner (thanks captain obvious)
that is presented in a pen style fashion with a felt tip applicator which is my preference when it comes to liquid liners as it is far easier to control and use.
The nib has a great sharp point that allows you to create precise lines in various widths.

Stay All Day Waterproof Liquid Eye Liner comes in various shades - if you want to be one step ahead from the rest I suggest picking up Moss as green is predicted to be huge in terms of cosmetics in 2013
but I would imagine that the black shade is the best selling option.
Stila Intense Black is close to a true black but truthfully it is not the best pigmented liner I have ever used (Inglot's Gel Liner has that accolade) but as far as liquid liners go it does offer good colour pay off.

I agree with Stila's statement that it glides on easily and does not tug at the eyelids
but it is not the quickest drying liner out there which does make it a little subject to smudging and smearing.
However ones it sets (give it a minute or two) it lives up to the waterproof and stay all day claim,
wearing for close to 10 hours on my oily lids.

Stila Stay All Day Waterproof Liquid Eye Liner in Intense Black* £14/0.4ml via Stila - link