What do the Referendum, Primary, Recall, Initiative, and the 17th amendment all have in common?

Initiative is a process which citizens can bypass their state legislature by placing proposed statutes and constitutional amendments on the ballot, directly and indirectly.

Referendum refers to a measure that appears on the ballot, can be a legislative referendum, where a measure that goes to the voters for approval while the popular referendum is on the ballot because of a voter petition.

Recall give citizens the oportunity to remove and replace a public official prior to the end of a term of office.

Primary are used for political party members and voters choosing who they want to go on the ballot.

The 17th amendment enables regular voters to elect who they want as their Senators rather then representatives.

Referendum, Primary, Recall, Initiative, and the 17th amendment all have in common the citizens participation as voters.