A search engine is a web site that collects and organizes content from all over the internet Search engines look through their own databases of information in order to find what it is that you are looking for. “Search engine” is the popular term for an Information Retrieval (IR) system.

Search engines match queries against an index that they create. The index consists of the words in each document, plus pointers to their locations within the documents. This is called an inverted file.

A search engine or IR system comprises four essential modules: A document processor A query processor A search and matching function A ranking capability

Archie -> First search tool for the Internet Gopher -> Indexed plain text documents Jughead -> Searched the files stored in Gopher index Wandex -> First Web search engine systems

Alan Emtage created the first ever search engine called Archie in Archie collects information by crawling the internet. It matches the files it found with search queries and returned results from its database. Archie

It was introduced in 1990 It is the protocol system It allows text files to be hierarchically organized It is used to enable the simple sharing of documents with which could be located in any part of the world Gopher

Jughead It was developed by Rhett Jones in 1993 Jug head is the search engine system for the gopher protocol It searches the single server at a time It was officially released in 2006

Wandex It was the first search engine introduced in 1993 by Matthew Gray It was the first search engine that is usable for world wide web Wandex itself was based on the world wide web wanderer which merely listed websites

A document processor A query processor A search and matching function A ranking capability

The document processor prepares, processes, and inputs the documents, pages, or sites that users search against. The document processor performs some or all of the following steps: Document Processor

Normalizes the document stream to a predefined format. Breaks the document stream into desired retrievable units. Isolates and metatags subdocument pieces. Identifies potential index able elements in documents.

Deletes stop words. Stems terms. Extracts index entries. Computes weights. Creates and updates the main inverted file against which the search engine searches in order to match queries to documents.

Query Processor Query processing has seven possible steps. System can cut these steps short and proceed to match the query to the inverted file. Document processing shares many steps with query processing.

More steps and more documents make the process more expensive for processing Search system designers must choose what is most important to their users, time or quality. Publicly available search engines usually choose time over very high quality, having too many documents to search against.

Step 1: Tokenizing Step 2: Parsing Step 3: STOPLIST Step 4: Stemming Step 5: Creating the query Step 6: Query expansion Step 7: Query term weighting

Search and matching function Searching the inverted file for documents meeting the query requirements It is the simple binary search It follows the simple document representation, query representation and algorithm After computing the similarity of each document in the subset of documents, the system presents an ordered list to the user

Crawler - Based Search Engines Human - Powered Directories Hybrid Search Engines " Or Mixed Results

Spid ers Robo ts

It is easy and quick It is a quick access to information Save of time It help to organize internet and individual websites

The search system development or selection should be based primarily on the local needs Consider using freeware search engines, if your requirements are met by these. Consider if the web server you are using supports indexing and search, and if this is adequate for you

The IT Professionals should make an effort to keep themselves abreast of the current web technologies The features available within a tool should be made use of properly to get maximum benefits

Search engine plays important role in accessing the content over the internet, it fetches the pages requested by the user. It made the internet and accessing the information just a click away.

The need for better search engines only increases The search engine sites are among the most popular websites.