All you need to know is that the Glencairn glass is used by EVERY whiskey company in Scotland and Ireland. This glass was SPECIFICALLY designed for whiskey by the whiskey industry.
The design
The glass was designed with the tapering top in order to lock the aromas in the glass, making it easier to savor your whiskey on the nose before savoring it in your mouth. The bulb-shaped center allows for better visibility to evaluate the colors. And finally the base of the glass makes it easy to hold with your index finger and thumb, thereby not artificially warming the whiskey with your body heat.
How to drink it
The Glencairn glass is meant to drink your whiskey neat or with some water, but not on the rocks. Actually if you’re still drinking it on the rocks then hopefully you know by now you shouldn’t.
For more information check out their official site.