A rapporteur is a person who is appointed by an organization to report on the proceedings of its meetings. The term is a French-derived word.
The rapporteur is an eminent role in the legislative process of the European Parliament (EP). They are a Member of the European Parliament (MEP) responsible for handling a legislative proposal - both procedurally and with regard to its substance - on behalf of the European Commission, the Council of the European Union or the EP. Based on the relevant proposal, the rapporteur is appointed by the relevant Committees of the European Parliament charged with drawing up a legislative recommendation for the EP to vote on. The rapporteur, therefore, has a substantial influence in the process leading to the adoption of EU-legislation.
Their key-functions are:
Political groups within the committee in charge with drawing up a legislative recommendation may appoint a shadow rapporteur to represent their views.
(References:) Oxford Online Dictionary