Resumen
Internet censorship or internet content filtering is used to protect people from harmful materials, such as child pornography, as well as defamation and fraud, which are easily perpetrated on the internet. However, implementing censorship creates technical and social issues, such as over-blocking or false detection, decreased network performance, and freedom of speech. This paper describes internet content filtering approaches and technical difficulties to implementation. This paper also discusses censorship and freedom of speech with actual examples.