These are explanations that apply to many dances.
Most of the dances described here require 2 people to form a couple. Conventionally this is a man and a woman (no ageism intended). However, it is common for women to dance together. It is also possible, though rare, for men to dance together. So man in this context merely means the person leading while lady means the person following. Note that lady is normally used in preference to woman - presumably because of the behaviour expected. Although gentleman isn't used instead of man, this does not imply that bad behaviour is acceptable.
Another important thing to note is that step groups or figures are named for what the man is doing. The lady is usually doing the opposite (in terms of foot and direction). The sexism is clearly deliberate but now too traditional to be changed. In the spirit of convention, where a diagram shows two people, the man will be blue/cyan and the lady will be red/magenta. In complex or animated diagrams, the paler colour will be used to highlight the moving foot of each dancer.
There is one tradition that really needs breaking. Conventional ballroom etiquette requires the man to ask the lady to dance. This is just not workable in a room of assertive women and shy men. Anyone should be able to ask anyone else to dance. Of course, it has always been permissable to refuse a dance - provided it is done politely.
The direction of dance steps and positions of dancers may be described in terms of a line of dance. This is an imaginary thing not a visible line painted on the floor (unless you happen to be in a gymnasium with courts marked out for various sports). By convention, the ballroom line of dance runs anticlockwise around the edge of a room. Typically the lady starts closer to the wall than the man, but positions change during the dance.
In any diagrams used here, the line of dance will be from left to right (like English text). So the wall would be below the diagram and the centre of the room would be above the diagram. The directions are then:
| diag. to centre against LOD | | to centre | | diag. to centre |
| against LOD | | along LOD | ||
| diag. to wall against LOD | | to wall | | diag. to wall |
A reasonably large room is required for dancing - eg school or church hall. Though Argentine Tango is supposed to fit on a table top. A sprung wooden floor is best (especially for those with suede-soled shoes). Use the space like fairground Dodgems not Bumper-cars. The man should remember that the lady is not to be used to clear a path for him through other couples. This seems to be a common mistake among beginners and advanced dancers alike.
For Ballroom and Sequence dances the flow follows the line of dance anticlockwise round the edge of the room. Couples make small incursions towards the centre or mad dashes across the diagonals (if not Sequence). This leads to occasional whole body collisions.
In Latin dances the couples distribute themselves randomly round the room. Each couple has their own nominal line of dance which moves with them. This leads to more frequent collisions of extremities.
In Solo or Line dances the individuals should fill the available space in neat rows, all facing the same direction. Each has their own line of dance which rotates in synchronisation with everyone else's. Collisions shouldn't occur at all. Folk, Country or Barn dancing should be similarly tidy but with several people in each set/group sharing a line of dance.
These are conventional descriptions of step speeds (and are relative within a dance style). They are abbreviated to S and Q. A Slow is usually one beat of a 2 or 3 beat bar and two beats of a 4 beat bar. A Quick is half a Slow. In dotted rhythms, Slow and Slow means 3/4 + 1/4 + 1 beats (or 2/3 + 1/3 + 1 beats). Quick and Quick is half this. Sometimes the man and lady are using different timings. For example, the brush step in a spin turn takes part of the previous Slow count as if it was 2 Quicks instead.
From the slow and quick point of view, the 4 beat bar of a Cha-Cha is counted as 2 half bars, with percussion also marking the half beats. So a slow is 1 beat and a Quick is 1/2 a beat. This gives SSQQS (or Step Step Cha Cha Cha) for the typical rock step and chassé combination.
When the couple rotate clockwise (to the right) this is a natural turn. When the couple rotate anticlockwise (to the left) this is a reverse turn. Whatever the direction of rotation, the size of step is very important. The person on the outside of a turn must take a large step while the one on the inside takes a small step. This is vital for the Viennese Waltz and is one reason why beginners fail to make turns. The simplest way to remember is to follow a forward step with a large side step and a backward step with a small side step. Only in a pivot or rocking turn will partners have the same size of step.
Many steps and step groups or figures involve some amount of turn. For example, basics in Rumba and Cha Cha are supposed to rotate slowly anticlockwise.
An inline step (left or right) is straight in front of the body. The other person (man or lady) has to move their opposite foot out of the way. With the couple slightly offset from each other, it may be more like a step between the partner's legs.
An outside step (right or left) is across and in front of the body. It is outside the body and legs of the partner, who should be crossing their opposite foot (left or right) behind. This means the same leg of each person is adjacent, right to right or left to left. However, the upper bodies often remain facing by twisting at the hips.
Many dances include walks forwards and backwards. Forward walks are just what you might expect - placing one foot in front of the other, transferring weight and then repeating with the other foot. In the Samba there is a special type of walk that is very different. Backward walks are usually a reversal of normal walking - with a few exceptions. In the Tango walks curve to the left and, when going backwards on the right foot, the right toe needs to be tucked in. In the Foxtrot the heels are dragged back first, as in Michael Jackson's Moonwalking.
A check step begins with a walk forwards, backwards, across or sideways. However, instead of proceeding onwards, the next step reverses the first one. So weight is transferred onto the moving foot and then replaced onto the original foot. It is quite common in the Foxtrot in order to change direction. The rock step in some Latin dances and Rock 'n' Roll is similar. The timing is usally quicker and weight may not be transferred fully onto the checking foot before replacing. A hover step seems to be merely a check when up on the toes or balls of the feet (but possibly including some turn). Again, weight may not be transferred fully.
A lunge is a much longer and heavier check step used mostly in the Tango but also Rock 'n' Roll. The man is usually going forwards. Both man and lady bend the supporting knee on the lunge.
The chassé is a step + close + step combination. Take a step sideways, close by moving the other foot next to the first one and then repeat the original step. The timing is quick quick slow in most dances but is quick and quick in the Jive. It is usually a sideways move although it can be forwards and backwards (eg Argentine Tango).
It is more normal to use a lock than a chassé when going forwards or backwards. The timing is the same but the lock movement replaces the close. When going forwards the locking foot is tucked behind the stepping foot so that the legs cross slightly. When going backwards the locking foot is tucked in front. A lock is danced on the balls of the feet with the heels raised so that the legs can touch while crossed.
The whisk is a step to the side followed by the other foot being crossed closely behind it. In Ballroom the step is always(?) in the same direction but is named for the step the man takes before it - left foot forward or back. In Latin the whisk is used in both directions but is named for the man's sideways step - left or right. The crossing behind is quicker and weight is immediately replaced onto the other foot.
The man leads the lady to dance the figure he has chosen next. Even in a sequence dance, where no choice of steps is possible, the man should lead to indicate the next figure in the sequence. Leading is done by changes in body position and hand pressure or hand signals. All leads should be subtle not forceful.
Transferring weight to one foot (along with the inevitable slight sway) indicates the other foot is going to move next. This applies particularly to the beginning of a dance. If the dancers are close enough together, hip pressure during the dance will show which foot is moving. Sway and body angle indicate the direction of chassé steps.
With the man's right hand on the lady's back, a number of leads are possible. Releasing the fingers and pressing with the heel of the hand directs the lady to turn out to promenade position (eg for a whisk). Pressure on the fingers directs the lady to turn back in from promenade to closed position (eg at the end of a chassé). This is also the lead from closed position to step outside the man on the right. Pushing sideways with the hand directs the lady to step outside the man on the left (eg for a wing). Stepping flat (not rising to the toes) and pressing down with the hand to prevent the lady rising indicates a hesitation step.
The linked hands are used less in ballroom than latin. Pushing out with the left hand as a result of turning the top of the body is part of leading a whisk. In latin dances the linked hands are used to lead turns. Special hand grips indicate particular steps or figures. All these leads are far less subtle than the ballroom ones.
The lady is also permitted to lead under special circumstances. This is when she sees that the man is likely to step back into the path of another couple. In ballroom, the lady should use pressure with her left hand on the man's right shoulder to warn him. In latin, the lady can pull back a little on the linked hand(s).
CBM stands for Contrary Body Movement and CBMP stands for Contrary Body Movement Position. The first applies to a step when turning and the second to one that merely looks as if it is turning. Both mean that when a foot moves, the opposite side of the body should also move in that direction. I think this is a lot of fuss about nothing as it is effectively stating the obvious.
The important thing to remember when dancing is that most of the time your body has to go where your feet go. There is no point in stepping forwards on the right foot into a natural turn if you leave the left side of your body behind. It will be difficult and look ungainly to try and catch up on the next step. As a man, it will be impossible to lead the turn properly because your upper body is responsible for leading not the feet. Try thinking about where you want your body (and the lady!) to go first and then use your feet to get you there. Similarly when following as a lady, it should be obvious where the man wants your body to go so use your feet to achieve this.
Old-Time dances frequently use foot positions from ballet. The step notation I use in the dance instructions largely ignores this complication, but the accompanying diagrams do illustrate it. However, note that everywhere else a 3rd position is shown the same as a 5th because I couldn't be bothered to duplicate all the GIFs. So for anyone who cares:
 | 1st Position |
 | 2nd Position |
 | 3rd Position (right foot) |
 | 4th Position (right foot) |
 | 5th Position (right foot) |