This character is a Other Symbol and is commonly used, that is, in no specific script. The character is also known as archive.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. U+1F5C3 offers a line break opportunity at its position, except in some numeric contexts.
The CLDR project calls this character “card file box” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: box, card, file.
This character is designated as an emoji. It will be rendered as monochrome character on conforming platforms. To enable colorful emoji display, you can combine it with Glyph for U+FE0FVariation Selector-16: 🗃️ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
An index card (or record card in British English and system cards in Australian English) consists of card stock (heavy paper) cut to a standard size, used for recording and storing small amounts of discrete data. A collection of such cards either serves as, or aids the creation of, an index for expedited lookup of information (such as a library catalog or a back-of-the-book index). This system is said to have been invented by Carl Linnaeus, around 1760.