My Orthodox Jewish co-worker invited me to his wedding, but I've never been to a Jewish wedding before. Is there anything I should be aware about if I plan to attend?
Yes, there is plenty that is worth knowing ahead of time about Orthodox weddings. First, I'll talk a little about what will or might be expected from you at the wedding and then I'll talk a little about what to expect at a Jewish wedding and how it's different from a non-Jewish or non-Orthodox wedding (I'm assuming since you say you've never been to a Jewish wedding that you have been to non-Jewish weddings). I am not going to go into details of the wedding ceremony itself. Rather, I will give some practical advice for you.
Expectations of you
You won't have to worry too much about unexpectedly being asked to do something that you don't know how to do such as reading in Hebrew. The host of the wedding knows that you likely don't know how to do anything like that (and those honors are usually assigned ahead of time anyway).
One thing that you will want to take into consideration is your dress. Just like attendees of non-Jewish weddings, we dress up at Jewish weddings. The level of formality varies. If the wedding invitation doesn't mention "black tie" or anything like that, a nice suit or women's equivalent will suffice. This standard is the same as for a non-Jewish wedding. The one difference is that Jews do observe modesty laws. In order to show respect, you should do so as well. For men it's pretty simple. A regular suit will pretty much satisfy the requirements. Men should cover their heads with a kippah which will likely be available at the wedding venue. For women, dresses and skirts are to be preferred over pants and they should come down at least to the knee (possibly to the ankle, depending on the crowd) while shoulders should definitely be covered (no "strap" dresses) and in many communities arms should be covered down to the elbow. Tops or dresses that are cut low in the front or back should be avoided. How out-of-place you will feel if you don't follow these guidelines depends very much on the crowd. If the couple is newly religious, many of the guests (including family) may not be following them. On the other hand, if both spouses come from long religious lines and live in a religious neighborhood it is likely that everyone will follow them strictly. If you have any questions, your host undoubtedly be happy to give you more personally-tailored details.
Another point to note is that certain parts of the wedding may be separated by gender. It is very likely that the wedding dancing will be separate by gender, and the wedding ceremony itself may be as well. There are probably not going to be signs telling you where to go; just follow what everybody else is doing. If men and women are separating, go to the appropriate area.
What to expect
In some ways Jewish weddings are similar to non-Jewish weddings, but in other ways they are very different. Usually the wedding will start with some time where the bride and groom are sitting in separate rooms and there is food in both. Where the guests go during this time varies; just do what everyone else is doing. In some cases, all of the men will be in the room with the groom while all the women will be in the room with the bride. In other cases, the room with the groom will have all of his close male friends and relatives while everyone else will be in the room with the bride. Again, just follow the crowd. If there's a large group of people of both genders hanging out and eating somewhere, that is definitely an appropriate place for you to be. Otherwise, find the place with people of your gender and help yourself to food. During this time, both spouses' parents will likely meet in the room with the groom and sign some documents. Then some other people will sign some documents. One last thing to note about this time: it usually lasts for quite a while... often an hour or more. It is not expected that you arrive at the very beginning of this time.
After some time has passed, the groom will go see the bride and then everybody will move on to the place where the wedding ceremony itself will take place. For this, just follow the crowd. If people are sitting separately by gender at the ceremony, do so as well.
Jewish wedding ceremonies are actually quite short. Often no more than 20 minutes or so. Some prayers and blessings will be said, a couple of songs will be sung, and someone might say a few words of Torah. Then the groom will step on and break a glass and that will be it. You don't have to do anything in particular during this time. Just sit and watch.
Finally, the meal and dancing part of the wedding will occur. The bride and groom will be in seclusion for a few minutes together during which time an appetizer course is often served to the guests. Once the bride and groom come back into the room, the dancing will begin! Dancing will likely be separated by genders with a curtain or free-standing wall separating them. Go to the appropriate side and have fun! Dancing at Orthodox Jewish weddings is quite different from dancing at non-Jewish weddings. It is fast and frenetic and there is no slow-dancing. You definitely want to be wearing comfortable shoes. Jackets and ties often come off for this part and you can expect to sweat significantly if you participate. During a part of the dancing, there will be a moment when the bride and groom are brought to sit next to each other and people take turns doing silly things to entertain them. You can participate in this if you want if you are a man, though in many communities women do not participate. This is another one of those cases where you just see what others are doing.
At some point during the wedding, an announcement might be made that people are going to take a break to pray. This could be at any of the transition points or possibly during the meal. The announcement might mention the words "mincha," "ma'ariv," or "daven." If you aren't Jewish, you can ignore this announcement. If you are Jewish, you might want to join in the prayer. You can ask if someone has an extra prayer book (with an English translation, if you need it). Occasionally the prayer service might take place in the main room with everyone, though in my experience this is rare. If you are not Jewish and this happens, it's best to stand when people stand and sit when they sit. The prayer probably won't take more than 10 minutes.
Once everything is done and the meal and dancing are over, everyone will say the Grace After Meals. There are a few special blessings at the end of this that are special for weddings. Usually these are assigned ahead of time, but in some cases they aren't. If someone asks you if you want to say one of the blessings but you are not Jewish or simply cannot read Hebrew, you can simply politely decline. Nobody will be offended.
Typically the entire wedding will last somewhere between 3 and 6 hours.
All of the above is typical of an Ashkenazi wedding in the United States. Ashkenazi weddings in Israel are likely to be similar though the dress is likely to be less formal if the families are not American immigrants to Israel (and possibly even if they are). In Israel it is relatively common for people who weren't invited to the wedding to show up after the meal to participate in the dancing. Some people might also be specifically invited to this part. If someone verbally invites you to "come dance at my wedding," but doesn't send you a wedding invitation, this is likely what they mean.
Finally, Sefardi weddings are quite different from Ashkenazi weddings. They are more likely to start late and much more likely to last much longer. In general, though, if you follow the rule of "do what everyone else is doing," you will be able to get through any Jewish wedding and hopefully have a great time!
To supplement, not supplant, Daniel's good answer:
- Orthodox Jewish weddings start late. (Even later, often, if the bride and groom are Sephardic.) This varies geographically; for example, in my experience, ceremonies start almost on time in St. Louis, Missouri, but as much as an hour later than scheduled in New York City and environs. It may also vary by other factors. You may wish to ask someone close to the bride or groom what to expect in this regard.
- (This one applies only if you read Hebrew and the wedding is of Chabad-Lubavitch folks.) Chabad-Lubavitch invitations in the United States are often bilingual in Hebrew and English, with different times listed on the Hebrew side and the English side. Ignore the time listed on the Hebrew side; the time listed on the English side is correct (but is then subject to the preceding item in this list about starting late).
- You will see people pouring water over their hands at the start of the meal. This is to fulfill a rule of Judaism about pouring water over one's hands before eating bread. If you're not Jewish, there's no reason for you to do it. If you are Jewish, and wish to honor the couple by doing something they would likely appreciate if they knew about it, then by all means go ahead. Probably someone standing around will be glad to show you how if you say something like "What do I do here?", but basically you fill a cup with clean water, pour it over all parts of your right hand, refill it if necessary, pour it over all parts of your left hand, and wipe them dry.
- Most Orthodox weddings in my experience do not have an elaborate or large wedding cake. However, you may possibly see slices of bread handed around, either near the start of the meal or soon after the first dance after the bride and groom join the meal; feel free to take or decline a slice without showing any offense.
Other items to add that MAY occur:
Some have a custom that if the bride and / or groom is / are the last child being married, they will do a "mezinkeh" ceremony. Customs on this vary, somewhat. Usually, the mother of the child wears a wreath on her head, and people dance with the parents and bride / groom to a special tune. Often, one of the dancers brings a broom to symbolize "sweeping the house clean".
Some "yeshivish" weddings have extra dancing after the Grace after meals where certain friends are invited for a "chassunah tanse". These friends are not invited for the rest of the wedding, but they come at the end to dance with the couple.
While not directly wedding related, if you are comfortable enough and on a good friendship with the groom or bride's parents, you could ask if you can take any untouched deserts. I mention this having had a lot of experience attending many weddings and my family knowing many caterers. Because of health rules, once a cake comes out of the box, even if untouched, it must be disposed afterwards. This is a shameful waste of food. So, if your host permits an you can use it, ask. If you can't personally use it, think of a friend, needy person or synagogue that can. (I've donated items to a neighborhood family who was extremely grateful. Turned out that they were planning an engagement party a day later.)