If we believe the statistics, since the start of their electoral term in July 2004, MEPs have voted more 12,000 times in 33 plenary sessions. European Parliament voting is mainly via a show of hands, like the Greek assembly under Pericles. The session president casts an eye over the raised hands and judges where the majority lies, without counting the exact number for or against. When a simple majority is required (a majority of the members present) it is generally quick and simple.
 
But sometimes the vote is tight and the decision of the president might be contested by MEPs who raise their hands and call out “check, check!” Also,if the President decides that the result is doubtful, the President may decide to hold the vote again using the electronic system and, if the latter is not working, by sitting and standing. MEPs no longer raise their hands, instead they press a button (for, against or abstaining) in the special box on their desks. Each MEP must identify themselves by sliding an electronic card into the box.
 
Who voted for and who voted against?
 
With an electronic vote, the exact voting figures are displayed on screens in the room. This system is useful for votes which are contested and absolute majority voting (half plus one of the total number of members). It is indispensable for qualified majority voting (a specific majority, for example, two thirds of votes). The type of majority depends on the kind of decision and the subject of the vote. Even with electronic voting, anonymity is preserved and it isn't possible to know how each MEP voted. 
 
The vote of each MEP is only registered in the minutes when there is a roll-call ballot. The term comes from the era when the president called on each deputy by name to give their vote. The president would say “Mr Smith” and Mr Smith would get up and give his yea or nay. You can imagine how long this system of voting would take with 736 MEPs. Electronic voting allows us to avoid never-ending sessions. 
 
MEPs may also vote via a secret ballot, by placing their voting paper into a ballot box. In principle, this type of vote is reserved for nominations. But all votes may be conducted in secret if at least one-fifth of the MEPs so request. The count of ballots is made by two to six tellers chosen by lot from the MEPs.
 
How do the MEPs work it all out?
 
More than 18,000 documents and 16,000 amendments covering legislation in all areas of the EU have been put before MEPs since July 2004. It isn't possible to be a specialist in everything, that is why the political groups in the Parliament (MEPs are grouped by political affiliation and not nationality) have coordinators for specific areas (internal market, industry, agriculture and so forth).
 
They also nominate “rapporteurs” who draw up reports on all the important dossiers. The coordinators and rapporteurs draw on their knowledge of the subjects to prepare up a voting list, for members of their party, on which they indicate which way to vote in line with party policy.
 
During the plenary, you can see them giving the thumbs up or thumbs down to the various pieces of legislation being voted on - just like Jean-Léon Gérôme's “Pollice verso” painting. Only, instead of deciding the life or death of a gladiator, the thumb is just an indication to the MEPs in the same group on which way to vote. But, at the end of the day, it is up to each member to decide whether or not to follow the suggestion of the group.