Which of the following describes estoppel?

Estoppel is a legal principle that prevents a person from arguing something contrary to a claim made or implied by their previous words or actions. It essentially upholds consistency and fairness in legal proceedings by ensuring that one cannot deny a fact that they previously acknowledged or admitted, especially when another party has relied on that admission to their detriment. Therefore, the description that aligns with estoppel is the one that states it prevents the denial of a fact previously admitted.

In contrast, the other choices relate to different legal concepts. An agreement to pay on behalf of another party refers to a suretyship or guaranty, which involves a third party agreeing to be responsible for another's obligation. Intentional misrepresentation involves knowingly providing false information, which can lead to deception and legal repercussions but does not directly relate to estoppel. Hiding material facts pertains to withholding critical information, which can mislead others, but again, this does not capture the essence of estoppel. Thus, the original choice emphasizing the prevention of denying previously admitted facts accurately portrays the function of estoppel within legal contexts.