Type of mouse that has a ball located on the bottom that rolls around on a flat surface as the mouse is moved. Sensors inside the mouse determine the direction and distance of the movement - Input. Optical mouse. Type of mouse that uses a laser to detect the mouse's movement and has no moving parts - Input.
The Strategic Defense Initiative (SDI) was a proposed missile defense system intended to protect the United States from attack by ballistic strategic nuclear weapons (Intercontinental ballistic missiles and Submarine-launched ballistic missiles).
DEFINITION of 'Human Development Index-HDI'. A tool developed by the United Nations to measure and rank countries' levels of social and economic development based on four criteria: Life expectancy at birth, mean years of schooling, expected years of schooling and gross national income per capita.