Upgrade is a verb meaning to raise something to a higher standard, in particular to improve (equipment or machinery) by adding or replacing components.
In computing, an upgrade refers to the process of replacing a product with a newer version of the same product.
The term "upgrade" also refers to:
1. An upward slope or grade
2. The act of improving something (especially machinery) by adding or replacing components
3. A reservation that is improved to a better class or category