Mint extract is basically the bottled essence of the mint leaves. It is used as a flavoring agent in multiple mint recipes from drinks and desserts to candies or simply dripped into a cup of coffee.
Most extract recipes call for the use of alcohol in one form or another as does this recipe. However if you are squeamish or have reservations about using alcohol you can also use vinegar for an alcohol free extract - scroll to page bottom if that be the case.
Note that if you opted to use dried mint leaves instead of fresh you will cut down on the waiting time by roughly half or end up with a much more concentrated extract.
There are also alcohol free mint extracts that are easily made. One that works well involves diluted vinegar [either white vinegar or cider vinegar will suffice] to roughly half strength. Water - Vinegar 50/50 blend. Follow the instructions above and substitute the water-vinegar blend for the Vodka. The vinegar will detract from the mint flavor of the extract, even in its diluted state, some people will add small amounts of Honey as well.
I personally prefer the Vodka blend but I have tried the vinegar version and it is acceptable - the second batch I made I added some Stevia leaves which helped to stifle the pickly vinegar flavor.