Tickets are found in many encrypted files used by the Wii (e.g. [[WAD Files]] or [[Wiidisc]]s). They contain the encrypted [http://en.wikipedia.org/wiki/Advanced_Encryption_Standard AES] "title key" and the Title ID of the data and are signed by a certificate from a [[certificate chain]] (which usually is the same for all titles and stored somewhere on the NAND).So far only tickets with [http://en.wikipedia.org/wiki/RSA RSA-2048] signatures have been seen. (Discs will only work with those signatures because the size of partition ticket is always 0x2a4)
While all Wii titles are available on [[NUS]], most are encrypted with a key found in the ticket; this key is what is purchased with the [[Wii Shop Channel]]. Deleting a title using the data management feature of the [[System Menu]] leaves the ticket intact; this is responsible for allowing software to be redownloaded. However, tools such as [[AnyTitle Deleter]] delete tickets when they delete titles, which removes all traces of the title.