The Vietnamese language is written with a Latin script with diacritics (accent tones) which requires several accommodations when typing on phone or computers. Software-based systems are a form of writing Vietnamese on phones or computers with software that can be installed on the device or from third-party software such as UniKey. Telex is the oldest input method devised to encode the Vietnamese language with its tones. Other input methods may also include VNI (Number key-based keyboard) and VIQR. VNI input method is not to be confused with VNI code page.
Historically, Vietnamese was also written in chữ Nôm, which is mainly used for ceremonial and traditional purposes in recent times, and remains in the field of historians and philologists. There have been attempts to type chữ Hán and chữ Nôm with existing Vietnamese input methods, but they are not widespread.[1][2] Sometimes, Vietnamese can be typed without tone marks, which Vietnamese speakers can usually guess depending on context.