Straight angle is a straight line. It has measure 180 °
At the picture angle ABC is straight angle
Right angle is half of straight angle.
It has measure 90 °
At the picture angle DEF is right angle.
Acute angle is less than straight angle. It has measure less than 90 °
At the picture angle LMN is acute angle.
Obtuse angle is bigger than straight angle and less than straight angle. It has measure bigger than 90 ° and less than 180°.
At the picture angle XYZ is obtuse angle.
Adjacent angles are called angles like a and d, or a and b or b and c or c and d Sum of adjacent angles are equal to straigth angle(180°), so a = b and c = d.
Vertical angles are a and c or b and d. Vertical pair of angles are equal i.e. a = c and b = d
Let's have two parallel lines intersected by third line. Angles m and q or n and r or o and s or p and t are called corresponding. They have the same measure.