The English orthography is called Latin for historical purposes. Writing systems used by other languages are called non-Roman scripts (NRS). For computers to deal with NRS correctly, the document format, applications, keyboards, and fonts all have to cooperate.
“Mojibake” is the term for when a computer tries to deal with a character it doesn’t understand. This used to be common, but Unicode is a standardization of all characters used in human writing systems. UTF-8 has replaced ASCII as the dominant character encoding in modern computer systems. SIL has been deeply involved in NRS and Unicode development.
Creating software which will correctly deal with NRS is complex. Internationalization (i18n) is the process of ensuring that all language-specific content is extracted from software into configurable resource files. Localization (L10n) is the process of preparing software to work in a specific language.
On Android, Multiling Omni Keyboard is the defacto standard for NRS; it is available free from the Google Play Store and supports hundreds of languages. Keyman is the equivalent for Windows. It is free to SIL-affiliated organizations, but has a low price for general use. MSKLC is an old but serviceable free solution for simple keyboards on Windows.
Android, Linux, and Apple all ship with robust Unicode fonts. Microsoft has never shipped Arial Unicode MS standard with Windows, but it has been widely distributed with some versions of Office, so it is often present on Windows systems.
Windows 7 supports 35 languages and 55 LIPs, but licensing is an expensive hassle. Windows 8 supports 109 languages, removes licensing issues, and has many improvements for NRS. Windows 10 supports 106 languages, but requires Professional; international upgrades can also run into font issues.
Fierbaugh, Stephen. (2016, September 6) Fonts, Keyboards, and Non-Roman Scripts [Webcast]. In Tech & Field Brownbag Lunch Series. Arlington, Seed Company