Define position isomerism and provide an example.

(N/A) When two or more compounds differ in the position of a substituent atom or functional group on the carbon skeleton,they are called position isomers,and this phenomenon is termed as position isomerism.
Example: The molecular formula $C_3H_8O$ represents two alcohols because the same functional group $-OH$ is present,but its position differs.
Example structures: Propan$-1-$ol $(CH_3-CH_2-CH_2-OH)$ and Propan$-2-$ol $(CH_3-CH(OH)-CH_3)$.