Change in a business describes a change in action (new ways of working, new ways of handling tasks and processes etc.) with effects on the way of thinking and feeling for people inside the company.
Change can happen reactively or it can be shaped proactively. Often times change projects are set up to adopt new ways of working related to activities and processes within the company. The idea behind this is often to be better able to cater for client demands and preferences. This often implies that the requirements for teams and individuals change - both in terms of competences and ways of working. As a rule of thumb: The greater the change related to the Status Quo the more challenging the change for the company.
Here you can find examples of change projects in companies in which I have been involved.