Identify is an innate command that lets you give a second name to a specific object. It is particularly useful if you have a lot of similar objects (such as gold rings) for blorples or remembers, since it lets you distinguish between them easily.
An object's identity is not usually visible, showing up only if you use the "identify" or "locate" commands on it.
identify <object> as <some new name> identify remove [from] <object(s)> identify <object(s)> unidentify <object>
After you've given an object an identity, you can use that identity to refer to it--to get it out of a container, to cast spells or perform rituals on it, to hold it, and so on. The last word in the identity is the most important, and any other words in it are optional and can be in any order. For example, if you identify a blorple as "northwest corner of the roof of the drum", then you can refer to it by its full name, but you can also refer to it by "drum" or "roof drum" or "roof northwest drum". This can, of course, lead to conflicts if you also have a blorple identified simply as "drum"--typing "cast jpct on drum" could have you opening a portal from either one if both are in your inventory. As with normal names of items, you can use numbers to distinguish between them in a pinch--if you know that the first "drum" in your inventory isn't the one you want, you can "cast jpct on drum 2".
It can create problems if you use a number as the last word on a multiple-word identity. For example, if you have something identified as "drum 2", then you will be able to refer to it as "2", but you will not be able to refer to it as "drum 2", because "drum 2" will have the parser looking for the second item named "drum", and your "drum 2" cannot be referred to as just "drum".
If you've forgotten what you identified something as, you can "identify <object(s)>" to see what it is. Or, if you like, you can also "locate" it--for example, if you have several gold ring blorples in various places in your invetory and you can't remember exactly what you called one of them or where you put it, you could "locate gold rings" or "locate every gold ring", which will tell you the location and names of all the gold rings you have, anywhere.
Identities are preserved over logins, but the helpfile warns that they will vanish if the item leaves your inventory. In practice identities tend to be a bit more robust than that, and may be preserved even if you drop the item, sell it, or give it to someone else, but it's best not to depend on that.
An item may only have one identity, and multiple items may be identified as the same thing.
If you identify one or more containers as "component pouch", then spell components and ritual components will automatically be taken out of them when you cast the spell or perform the ritual that needs those components, if you don't already have some in your inventory. As of January, 10th 2017 non consumed components will be returned to the component pouch after casting a spell or performing a ritual.
If you have multiple containers identified this way, components will be taken out of both of them if necessary.