Consensus is a process for making decisions without voting. Its main feature is that no action is taken unless all members of the group can support the action or agree not to obstruct it. Most well-functioning groups actually use consensus informally most of the time. Majority rule groups often discuss things until most objections have been answered before taking a vote. An agenda item is discussed until the facilitator calls for a proposal.
Someone proposes a consensus statement.
The facilitator asks for any objections. At this point, any member may call for further discussion based on any reservations they may have. After any further discussion, the facilitator will again call for objections. If there are none, the statement is entered in the minutes as agreed to. This means that the member has some reservations, but will not obstruct the action being taken.