In the world of computing, you use commands to order computers around.
In the sub-world of fighting games, the input devices used are mostly a directional input (generally a joystick, hence it is often called the ‘stick’ or ‘lever’) and a few buttons. There are many arrangements and specifications used; in particular, special sequences of inputs work with particular games in particular ways. Because games tend to have a wide selection of these sequences per character, there are many commands listed in a ‘move list’.
The directional input is generally indicated by arrows each indicating one of eight directions (and occasionally the neutral “direction”); names and positions of the buttons will vary from game to game.
Between the arrows and button names on a command, there is a ‘plus’ symbol (+), indicating that they are to be input at about the same time: the naïve expectation (i.e. ignoring the buffer, command simplification, and situations where the execution is not possible) is that if you input the directions as indicated by the arrows and hit the proper button at the same time as the last direction, that move will be activated.
There are also indicators where you are expected to hit buttons and/or directions in a (generally rapid) sequence; I tend to use a comma (,), whereas Japanese sources tend to use an interpunct (・). I call these “chains”, though there is some semantic argument over what exactly a chain is (with some insisting it can only refer to a chain combo). Of course, you will eventually come across doubled or even tripled directions without these symbols; in these cases, they are implicit because it doesn’t make sense otherwise and it would look a little more unwieldy with them.
Particularly in 3D fighting games, you will see other indicators such as a star (☆) and empty/filled arrows. The former indicates returning the stick to the neutral position; the latter indicate how long the direction should be input: filled (black) arrows generally mean the direction is held a little bit, and empty (white) arrows generally mean to tap the direction as quickly as possible.
Commands listed on things such as the manual or arcade instruction card should always be considered to be for a character facing to the right (1P side). When you read less professional publications (such as Internet strategy guides...), you will find that this is generally the case, too, as a matter of unspoken agreement; however, not everyone is out to make things easy to understand. The potential confusion may arise in that the proper directions do a mirror flip left-and-right when the character faces left. For example:
On computers, where it isn’t always convenient to show nice, thick, readable arrows (and where character sets may even make make arrow indication highly impractical), directions are often indicated with numbers. These are often given unexplained, because it is assumed that the reader knows about this numpad notation; however, this is generally a great source of confusion for absolute beginners.
In reality, the naïve interpretation of commands is only a mental representation; to make the games actually playable by humans (or conversely, to make human input actually manageable for the game to read), developers implement a generally linearly-thinking ‘buffer’ for command input.
Thus, let’s say you input only the stick portion of a move command. Then, during the time the button input would normally be accepted, let’s say you input a different stick sequence, and then push the button. In this case, the general behavior would be for the sequence done first to be given precedence.
On a character for whom there exists both a “ + P” and a “ + P” command, a “ + P” input will yield the “ + P” because its directions came first. So when you wish for a “ + P” command immediately after, say, a dash, you may well misfire with the “ + P”; it is often possible, fortunately, to fudge around this with something like a “ + P”.