1. EVM (Electronic Voting Machine): A machine used in elections for casting votes electronically instead of paper ballots.

2. VVPAT (Voter Verifiable Paper Audit Trail): A device attached to the EVM that shows a paper slip so voters can verify that their vote has been recorded correctly.

3. First-Level Checking (FLC): The initial technical inspection of EVMs and VVPATs conducted before elections to ensure they are working properly.

4. Election Commission of India (ECI): The constitutional authority responsible for conducting free and fair elections in India.

5. Mock Poll: A test voting exercise carried out during FLC to check the proper functioning of the machines.