What is a conjugated system? Give examples and explain its effect.

(N/A) Conjugated system: The presence of alternating single and double bonds in an open chain or cyclic system is termed as a conjugated system.
Examples: $1,3-$butadiene $(CH_2=CH-CH=CH_2)$,aniline $(C_6H_5NH_2)$,and nitrobenzene $(C_6H_5NO_2)$ contain conjugated systems.
Effect: In such systems,the $\pi$-electrons are delocalized across the conjugated framework. This delocalization leads to increased stability of the molecule and can result in the development of polarity within the system.