solid-the arrangement of molecules is very tight or fixed and the molecules does not move
eg:solids like clock,brick etc
liquid-the arrangement of molecules is not tight as in solid but little loose.
eg:liquids like water,oil,milk etc.
gas-the arrangement is not there in gases as such and they move about freely.
eg:nitrogen,oxygen and other various types of gases etc
And also plasma is another state of matter but only the 1st three are important
Hope u liked it:)