A starter p5.js sketch displays a single white circle at the center of a dark 500-by-500-pixel canvas. It uses the p5.js library to create the canvas and draw the shape, with `createCanvas` setting the dimensions and `noLoop` preventing continuous redraws. The drawing occurs in the `draw` function, which sets a black background and fills the circle with light gray. This minimal example demonstrates basic p5.js rendering of static vector shapes.