The average length of a smooth snake is about 60–70 centimeters (cm), making it one of the smallest and most thin species of snake. In general, they have a color that is between grey and a drab brown, and their backs have black patterns that seem like bars or two rows of dots. The "crown" marking on the head of a smooth snake is almost always in the shape of a heart and covers the whole top of the animal's head.
In most cases, a stripe called an eye stripe may be seen running parallel to the side of the head from each eye. The scales of the smooth snake are flat and smooth, in contrast to the scales of the grass snake and the adder, which have a ridge (sometimes known as a "keel") in the center of each scale. This gives the smooth snake its name.
The months of April and early May are often when smooth snakes emerge from their winter slumber. The majority of their diet consists of non-venomous prey such as common lizards, sluggish worms, and tiny mammals (particularly shrews and nestling rodents), all of which are ensnared and squeezed to death inside the coils of their bodies. September is the month that sees the birth of live young, which resemble their parents extremely closely. Smooth snakes may live for a very long time, and females do not often reproduce every year. The smooth snake is a stealthy species, and when it basks in the sun, it does so wrapped in the stems of heather plants, where it is perfectly disguised. This behavior contributes to the snake's ability to avoid detection