The wedding rehearsal is basically a "practice wedding".  It gives you an opportunity to figure out who is doing what, who stands where, when to enter and exit, which way to face, etc.  This rehearsal is key in making sure your actual wedding ceremony runs smoothly. 

What to practice
The officiant or wedding planner will show everyone where to stand during the ceremony and when to enter and exit, pace of walking, order of processional, etc.  Your officiant should go over what they will be saying and when to perform certain things such as the lighting of the unity candle.  Your musician should also learn when to cue certain music.  Your may invite your photographer to attend your rehearsal as well.  This allows him/her to see the layout and when certain events will occur so as not to miss a single shot! 

Each person needs to practice what they will be doing.  For example, the groomsmen and groom enter and stand in their places, the ushers escort the parents/grandparents of the bride and groom, the bridesmaids and maid of honor enter and stand in their places, the ring bearer walks down the isle with the pillow, the flower girl walks down the isle dropping petals, the father enters with the bride and then gives her away.  The bride and groom might also practice reciting their vows.  Singers might practice their song(s), readers practice their reading(s).   Bring items such as a few chairs to practice seating, mock bouquets, basket for flower girl, pillow for ring bearer, candles to practice unity lighting, etc.     

Who should attend?
All members of the wedding party including the bride, groom, best man, groomsmen, maid of honor, bridesmaids, flower girl, ring bearer, parents of the bride and groom, officiant, ushers, readers, singers, photographer, musicians/DJ.

Run through the ceremony as many times as you need to be sure everyone is comfortable with what they should be doing.  Everyone should pay close attention to their directions and don't hesitate to ask questions if you don't understand something.

Rehearsal dinner
After the rehearsal, everyone gathers together for a dinner, usually hosted by the parents of the groom.  It is a good time for both families to talk with each other, and a good time to toast the bride and groom. You may also choose this time to give your attendant's their thank-you gifts.  The dinner may be formal or casual- from a fancy banquet room, to a favorite restaurant, to a backyard BBQ.   

Who to invite
The guest list should include both immediate families, the wedding party and officiant and their significant others, and out-of-town guests.  You may also choose to invite more friends or extended family members.  Depending on the type of rehearsal dinner you have, you can either send out invitations or go by word of mouth.  Just be sure that everyone RSVPs so you will know how many mouths to feed!  

Ideas for dinner
BBQ theme
food- brisket, sausage, baked beans, chili, potato salad, burgers, hot dogs, kabobs
decorations- checkered tablecloths, paper plates, plastic utensils, lawn chairs, mason jars

Caribbean theme
food- jerk chicken, seafood, fruit, fried plantains, coconut cake
decorations- tiki torches, nets, tropical flowers, seashells, tropical fruit centerpiece

Chinese theme
food- egg drop soup, Mu Shu pork, Kung Pao chicken, fried rice, noodles
decorations- chopsticks, fortune cookies, chinese lanterns, chinese fans

Italian theme
food- salad, pasta, bread, italian cream cake, wine, tiramisu
decorations- wine bottles for flower vases, dried herbs, wine glasses, bottles of olive oil