This tag is intended to highlight a question about something that resulted in a "bricked" or damaged Pi hardware, so that others might be made aware of something that is not good to do with theirs.
The specific term "bricked" arises from some consumer electronics products that use some sort of "firmware" to determine how they operate. These products, when subjected to a (possibly unofficial) firmware update procedure which fails: either because the data is not correct for the unit, or the process gets abnormally interrupted, becomes permanently inoperable. That such devices may be somewhat cuboid serves only to emphasise the similarity in levels of activity to that of a standard household brick.
Usage of the term has become more generally applicable to any electric/electronic device that has been rendered permanently and totally inert.