The paper titled "Encoding using bits flowing in restricted environments (review study) was accepted by Prof. Dr. Alaa Kazem Farhan in the first International Conference on Information Technology and Science held by the University of Babylon under the auspices of the IEEE Foundation." The idea of ​​the research is summarized in that: Symmetric coding can be classified into two categories: stream and block. Stream encryption is faster and less complex than block encryption, so it is suitable for IoT. (IoT) The Internet of Things consists of many interconnected restricted devices that share and exchange data and information among themselves on an ongoing basis. Therefore, IoT devices must ensure basic security features to protect that information. In this paper, we conduct a study and comparison of stream coding methods. It is concluded that Fruit stream encoder has good resistance to known attacks, while Enocoro128 and F-FCSR have high throughput, plus WG, Grain and MICKEY-128 are faster and more suitable for restricted devices.