Horizontal lines 'go' perfectly sideways like the red lines pictured below.
Properties of Horizontal Lines
Equation of Horizontal Line always takes the form of y = k where k is the y-intercept of the line. For instance in the graph below, the horizontal line has the equation y = 1 As you can see in the picture below, the line goes perfectly sideways at y =1.
Equation : y = 1
is y = k where k is the y-intercept
Below are several examples of the equation and graph of different Horizontal lines
Equation : y = 3
Equation : y = 2