Volunteerism is the practice of providing time and skills for the benefit of other people and causes rather than for financial benefit. In an employment-related context, volunteerism is concerned with the methods and tools employers use to support employees that want to volunteer.
Many organisations provide time-off for volunteering, often a paid day or so a year. The company may also mobilise its own resources to allow the entire company to volunteer for a good cause e.g. a web design business dedicating part of its time to building websites for charities.