There are two possible ways in which to interpret this question.
First, we can look at it in terms of the mechanics of voting. There are three ways in which the votes of the members of either house of Congress can be recorded. First, there is a voice vote. Here, members simply say “yea” or “nay” when they are instructed to do so. The person who is presiding over the house at the time of the vote then states their opinion as to whether there were more “yeas” or “nays.” Second, there is a division vote. In this procedure, those voting “yea” and “nay” are asked to stand up in turn. The number of members standing for each option is counted. This is more accurate than a voice vote. Finally, there is a roll call vote or recorded vote. In this type of voting, each member must specifically state how they are voting. In this type, each member’s vote is recorded and publicized. This is the only method in which there is a record of how each member voted.
Second, we can look at this in terms of what response the member can give. Members can, of course, vote “yea” or “nay.” But they can also vote “present.” This means they are showing that they are present at the time of the vote but they are abstaining from voting one way or the other.