The concept of freedom of information emerged in the United States in the 1940s. At the beginning of the concept, it was used to express the free communication of information under the freedom of speech and press. However, when the US press tried to promote the free communication of information around the world, it was found that the government was the main obstacle. Therefore, the press began to turn its target to the United States, and then launched the right to know movement. Eventually, with the joint efforts of the press and the Congress, a law called the Freedom of Information Act was introduced to specifcally protect the right to access to government information. In this process, the concept of freedom of information is used as a reference to the right to know while being used to refer to the right to express, causing confusion in conceptual cognition and shaping corresponding legal practices. This is both a habitual result of the use of the concept and a result of the strategic use of the concept by the legislative promoter. However, as the right to know or the right to information is explicitly recognized by more and more national and regional constitutions and related laws, the concept of freedom of information should return to its original intention and become a proper term for expressing the right to express.