Step 1:
Pull your thumbs apart. (this represents the parents) Your thumbs will open because you and your parents are not destined to be together forever. At some point they will leave you in your life.
Step 2:
Now put your thumbs back together.
Step 3:
Repeat the same motion with your index fingers (this representing your siblings). Of course your index fingers will also separate because you are also not destined to be with your siblings for the rest of your life. They will move on and have families of their own.
Step 4:
Now put them back together.
Step 5:
Now separate your pinkies. (representing your future children) Of course these will also separate because your children will not be with you forever. They will grow up to have lives and families of their own as well.
Step 6:
Now put them back together.
Step 7:
Now for your "ring" finger. (representing your life partner) Try separating them as you did with the other. Can't do it can you? That is because your life partner is the one who is supposed to be with you for the rest of your life. They will be the one to be with you forever and through thick and thin.
Roman belief
According to the Roman belief, the wedding ring is worn on the fourth finger of the left hand because of a vein that we have in our left "ring" finger. This vein is called the vena amoris, meaning "the vein of love." It was believed that this vein ran directly to the heart and that the "ring finger" was the only finger that contained it. As romantic as that may sound, we now know that this is not true.
Fun Idea: Print this, and give your guests something fun to read on your wedding programs to give your guests something fun to read during any waiting time. Make sure to warn your photographer so you can get some keepsake shots of your guests trying to do this!
(Original Source)