Unlike other cancers, the vast majority of skin cancers have no potential to spread to other parts of the body (metastasize) and become life-threatening. There are two major types of skin cancer: basal cell carcinoma (the most common) and squamous cell carcinoma (the second most common). Melanoma is also a form of skin cancer but is far less common, though more dangerous, than the other two varieties.
The definition of backfill is material used to refill a hole, usually what was previously dug out of the hole. Dirt and gravel are examples of backfill. Backfill is defined as to return soil and other materials to a hole after it was dug.
In urban planning, infill is the rededication of land in an urban environment, usually open-space, to new construction.[1] Infill also applies within an urban polity to construction on any undeveloped land that is not on the urban margin. The slightly broader term land-recycling is sometimes used instead. Infill has been promoted as an economical use of existing infrastructure and a remedy for urban sprawl.