Example is that you want to invest in securities . One person ,who is insider, says you that invest in the shares of Uniliver Pakistan or PSO and say that he has confirmed information that the company is preparing to declear interim dividend.
This mean an insider is person who work in the company and he is not honest with company and give internal information to outsider to get some undue favour from investor in way of kinds or money.
Insider trading is simply when any person becomes able to influence the rate of securities by disclosing the information which was not dislosed previously. Such person may or may not be an interested person.