If you ask most hobbyists and even many professionals what constitutes a PC board, they'd probably say the copper tracks and the base on which they are etched. But there is often much more to a PC board than that. For a start, there are other layers. And we are not just talking about double-sided or multi-layer boards, either.

Silk screen

The "silk screen" layer is also known as the "component overlay" or "component layer". It is the layer on the top of your board (and bottom if needed) that contains the component outlines, designators (C1, R1 etc) and free text. This is printed on your board using a silk screening process. White is a standard colour but other colours are available upon request. You can even mix and match colours on the one board but that usually costs extra.

When designing your board, make sure that you keep all your component designators the same text (font) size and oriented in the same direction. When laying out your own component footprints, where possible, make sure that you add a component overlay that reflects the actual size of your component. This way you will be able to tell at a glance how close you can physically position your components. Ensure that all polarised components are marked and that pin 1 is identified.