What is this site? It is generaly simplier version of wikipedia. You will find there selected articles. Enjoy!
A substring index is a data structure which gives substring search in a text or text collection in sublinear time. If you have a document S of length n, or a set of documents
of total length n, you can locate all occurrences of a pattern P in o(n) time. (o(n) means less than O(n). See Big O notation.)
The phrase full-text index is also often used for an index of all substrings of a text. But is ambiguous, as it is also used for regular word indexes such as inverted files and signature files. See full text search.
Substring indexes include: