Within the workplace, trade unions are represented by two groups of officials. There are shop stewards; these are the elected persons by the members in that workplace to look after their interests. In most organizations, the stop stewards spend only part of their time on union business, carrying out their normal work for the rest of their time. The second group is of full-time union officials, employed by the union to look after all the members in their locality. They come into the workplace occasionally and only by invitation but their presence can be vital at crucial times during major negotiations or to head off disputes that are simmering.