Types of Angles
An angle is formed by two rays with a common end point. The rays forming the angle are called the sides of the angle and the common end point is known as the vertex of the angle.
The sides of the angle are AB and AC. The vertex is A. 
How to name the angle? We can name the angle

Degree is the unit used to represent an angle measure and it denoted by the symbol º. A full angle formed around a point measures 360º. The angle at point are classified based on their measures as follows:
Type 
Degree measure 
1. Acute angle  0º < x < 90º 
2. Right angle  x = 90º 
3. Obtuse angle  90º < x < 180º 
4. Straight angle  x =180º 
5. Reflex angle  180º < x < 360º 
Let us see few examples on each of the above mentioned type.
Acute Angle  Right Angle  Obtuse Angle 
Straight Angle  Reflex Angle  Interior Angles 
Exterior Angles  Reference Angle 