This character is a Math Symbol and is commonly used, that is, in no specific script.
The glyph is a canonical composition of the glyphs Subset Of, Combining Long Solidus Overlay. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is mirrored into Not A Superset Of. The word that U+2284 forms with similar adjacent characters prevents a line break inside it.
The Wikipedia has the following information about this codepoint:
In mathematics, a set A is a subset of a set B if all elements of A are also elements of B; B is then a superset of A. It is possible for A and B to be equal; if they are unequal, then A is a proper subset of B. The relationship of one set being a subset of another is called inclusion (or sometimes containment). A is a subset of B may also be expressed as B includes (or contains) A or A is included (or contained) in B. A k-subset is a subset with k elements.
The subset relation defines a partial order on sets. In fact, the subsets of a given set form a Boolean algebra under the subset relation, in which the join and meet are given by intersection and union, and the subset relation itself is the Boolean inclusion relation.