A placeholder can refer to different things depending on the context. Here are some of the most common meanings:

• Text: In typesetting and layout, placeholder text is text that temporarily "holds a place" in a document until the final text is available. It helps preview fonts, spoof an e-mail spam filter, or reserve a specific place on a web page or other document for images, text, or some other object. One of the most common filler texts is "lorem ipsum".

• Symbol: In mathematics and computing, a placeholder is a symbol or piece of text in a mathematical expression or computer instruction that can be replaced by particular pieces of information. For example, a placeholder variable "p" represents the result of a computation in progress.

• Person or thing: A placeholder can also refer to a person or thing that occupies the position or place of another person or thing. For example, a politician appointed to a vacant seat in the Senate may be considered a placeholder until the next election.

• Temporary data: In computer programming, a placeholder is a character, word, or string of characters that temporarily takes the place of the final data. For example, a programmer may use a placeholder as a temporary solution until a proper value or variable can be assigned.

Its important to note that the term "placeholder" can have different meanings depending on the context.