A more thorough explanation:

The Aguilar–Spinelli test is a standard used in criminal procedure to determine if hearsay, such as an informant's tip, is reliable enough to establish probable cause for an arrest or search warrant. The test has two prongs that must be assessed independently: the reliability of the information and the reliability of the informant.

For example, if an informant tells the police that a drug dealer is operating out of a specific house, the police must assess the reliability of the information (is there any other evidence to support this claim?) and the reliability of the informant (have they provided reliable information in the past?). If both prongs are satisfied, the police may have probable cause to obtain a search warrant for the house.

It's important to note that the Aguilar–Spinelli test has been replaced by a broader approach called the totality-of-the-circumstances test, which considers all relevant factors in determining the reliability of hearsay.