The Pen tool works by plotting either straight lines or Bezier curves. These are parametric curves based on math rather than a line of pixels, which means they can be scaled up or down with no change in quality (as such, all fonts are vector-based shapes). Photoshop calls them Paths, or Shapes instead if they form a block of colour.
There are three main types of line: straight, curved and pointed. To make a straight line [A] click between two points. To make a curved line [B], click and drag outwards from the point. To make a sharp point [C], Alt-click on the point of origin to remove the outward handle then click another point to take the path in the opposite direction. While placing an anchor point, you can…