They're STOVL airplanes. Short Take Off Vertical Landing. They can only take off vertically on exhibitions, when they're carrying no weapons and little fuel. For normal operations they need a short runway.
Off-topic, but the F-35 VTOL design is amusing to me in that it was designed by Russia, but they never made more than a prototype and sold the tech to the US where we've now used it to make planes to take on Russia.