I'm going to talk here about calling for Square Dancers. I'm learning to tell them what to do, in time to the music, without anyone straining any body parts.
Let me explain some terms about formations. Callerlab resources are available to precisely describe FASR, which simply is a description of exactly how the dancers are arranged in a square. But, if I don't need to be that specific, there are some terms I will use:
Lines - dancers are facing each other, holding hands, in two parallel lines of four dancers.
Boxes - dancers are in couples. Two couples are back to back with each other and facing the other two couples.
Waves - dancers are in two parallel lines of 4. Each dancer is facing the opposite way of the adjacent dancer.
Two faced lines - again the dancers are in two parallel lines. The couple on one end is facing in and the other couple is facing out.
Double pass thru - This is when the dancers can do a "double pass thru." Center couples are facing with the other two couples behind them.
Normal couples - when there are couples (facing the same way, together) they are called normal if there is a "boy" on the left and a "girl" on the right.
In Sequence/Order - if, looking from above, you imagine a four-cornered geometric figure connecting the boys, it might be a sqare, a rectangle, a diamond, or whatever. If the "boys", for example, are in the same order as when they started from their home positions, they are in sequence. This means that boy 4 is clockwise from boy 1 who is clockwise from boy 2. You can tell this by looking at any two adjacent boys. (And you can look at the girls to see if they are in order or not.)