Tamil keyboard

Tamil Keyboard is the keyboard layout used in Computers or any mobile devices to input Tamil language scripts. 
The keyboard layout approved by Government of Tamil Nadu is Tamil 99. InScript is the Keyboard layout standardized by Government of India for inputting text in languages of India written in Brahmic scripts.
Tamil keyboards are often bilingual keyboards, combined primarily with English Language for ease of access and use.
Tamil 99.
Tamil 99 is a keyboard layout approved by the Tamil Nadu Government. The layout, along with several monolingual and bilingual fonts for use with the Tamil language, was approved by Government order on 13 June 1999.
Designed for use with a normal QWERTY keyboard, typing follows a consonant-vowel pattern. The arrangement of the characters allow for fast and simple typing for users familiar with the script.
InScript.
InScript (Indian Script) is the standard keyboard for Indian scripts. It is a touch typing keyboard layout for computer. This keyboard layout is standardized by Government of India for inputting text in languages of India written in Brahmic scripts, as well as the Santali language, written in the non-Brahmic Ol Chiki script. It was developed by Indian Government and supported by several public and private organisations. This is the standard keyboard for 12 Indian scripts including Bengali, Devanagari, Gujarati, Gurmukhi, Kannada, Malayalam, Oriya, Tamil and Telugu etc.
Usage.
Windows 10.
On Windows 10, Go to Settings.> Time & Language.> Region and Language.> Add new language.> Tamil (India) or Tamil (Sri Lanka) and select install. Then click Tamil (India) or Sri Lanka and select the options. Now select the Keyboard you want (Inscript or Tamil 99). Note: Tamil 99 is only available in Windows 10 April 2018 Update and higher.
iOS.
On iOS, Go to Settings.> General.> Keyboards.> Keyboards.> Add New Keyboard, and select Tamil, Select the required keyboard, such as Tamil99, Anjal or InScript.