Digitization is the process of making a digital copy of a physical object — for instance, scanning a document, using a digital camera to photograph an artifact, or converting an audiocassette into a WAV file. Another common term for this process is reformatting.
Your goal here is to create a digital file that accurately represents the original item, using recognized standards that will keep the file usable for years to come. Keep in mind that this digital file will need ongoing care and storage, just as proper care and storage is still needed for the original physical object.