The collins glass is a tall, thin tumbler that usually holds between 8-14 fluid ounces. The collins glass tends to be a bit harder to find in many retail stores, more than likely because they're not extremely practical. The highball glass is a more standardized shape and size for most drinks, but the collins glass tends to be thought of as fancy and prestigious, often associated with a top shelf cocktail.

A great example of a collins glass cocktail is the Tom Collins.