Leaving your hand on the bowl can heat up the wine, derailing it from the optimal serving temperature.
The glass you use and how you hold it can affect the wine tasting experience. Typically, your glass will come with a stem. This is where you should hold it. Leaving your hand on the bowl can heat up the wine, derailing it from the optimal serving temperature. The most important aspect when it comes to your chosen glass is that it should have a rounded bowl (to aid swirling the wine to release aromas) and inward-sloping walls (to concentrate those aromas).