of the same type. In communications and information processing, encoding is the process by which information from a source is converted into symbols to be communicated. Decoding is the reverse process, converting these code symbols back into information understandable by a receiver. One reason for coding is to enable communication in places where ordinary spoken or written language is difficult or impossible. For example, semaphore, where the configuration of flags held by a signaler or the arms of a semaphore tower encodes parts of the message, typically individual letters and numbers. Another person standing a great distance away can interpret the flags and reproduce the words sent. Obfuscation Encryption Steganography Identity Based Hiding the parties to a communication – preventing identification, promoting anonymity "Crowds" and similar anonymous group structures – it is difficult to identify who said what when it comes from a "crowd" Anonymous communication devices – unregistered cellphones, Internet cafes Anonymous proxies Hard-to-trace routing methods – through unauthorized third-party systems, or relays Hiding the fact that a communication takes place "Security by obscurity" – similar to needle in a haystack Random traffic – creating random data flow to make the presence of genuine communication harder to detect and traffic analysis less reliable Each of the three types of security is important, and depending on the circumstances, any of these may be critical. For example, if a communication is not readily identifiable, then it is unlikely to attract attention for identification of parties, and the mere fact a communication has taken place (regardless of content) is often enough by itself to establish an evidential link in legal prosecutions. It is also important with computers, to be sure where the security is applied, and what is covered. Borderline cases A further category, which touches upon secure communication, is software intended to take advantage of security openings at the end-points. This software category includes trojan horses, keyloggers and other spyware. These types of activity are usually addressed with everyday mainstream security methods, such as antivirus software, firewalls, programs that identify or neutralize adware and spyware, and web filtering programs such as Proxomitron and Privoxy which check all web pages being read and identify and remove common nuisances contained. As a rule they fall under computer security rather than secure communications. Tools used to obtain security Encryption Encryption is a method in which data is rendered hard to read by an unauthorized