A simple parabola with its vertex at the origin and its curve opening upward can be expressed with this equation:
y = x2
A more complicated equation for a parabola would look like this:
y = a(x - h)2 + k
This version for the equation of a parabola is often said to be in 'standard form'.
Here is EZ Graph with both of those functions preloaded (click 'Draw graph'):