The third sector, also known as the voluntary sector, is a sociology and personal capital, which refers to institutions that are neither government units nor private enterprises except the first sector or the public sector, the second sector or the private sector. Although the definition of the third sector varies from country to country, in general, most of the third sector units are funded by the government or private enterprises and maintained by non-governmental units. Ordinary corporate bodies, foundations or non-governmental organizations usually belong to the category of the third sector. Although the background and operation mode of each third sector unit are different, in general, the third sector unit usually has the characteristics of taking social welfare as its purpose and not paying taxes. Those institutions that aim at serving the public, not for profit, and whose income is not for personal gain can be classified into the third sector.