Civil liability in electronic communications is one the most important issues of Information and communications technology (ICT) law. Civil liability may be arisen from different causes such as copyright and trade mark infringement invasion of privacy and defamation. When discussing civil liability, two different civil liability systems may be considered: direct and indirect civil liability. In electronic transactions, the roll and legal situation of electronic communications service providers and intermediaries (such as internet service providers (ISPs), access service providers (ASPs) and host service providers) is very important. Liability of intermediaries and service providers are typical examples of indirect liability. On the other hand, indirect liability is of following types: contributory or vicarious. So, principle discussion in this article is to study about general principles of intermediaries' liability. for this, we have studied legal system of Iran as well as some other countries such as USA, Australia, UK, France, European Union and many international documents.