Euclidean triangles are a type of triangle defined in the context of Euclidean geometry, which is the study of flat surfaces. A triangle consists of three straight sides and three angles. The sum of the interior angles in any Euclidean triangle is always 180 degrees, regardless of the triangle's shape or size. There are three main types of Euclidean triangles: scalene, where all sides and angles are different; isosceles, which has two equal sides and angles; and equilateral, where all sides and angles are equal. These classifications help in understanding the properties and relationships of triangles in geometry.