Journal of Computer Applications (JCA) ISSN: 0974-1925, Volume IV, Issue 1, 2011  Abstract— The Internet is a huge collection of data. To get the appropriate information from it, using a search engine is the most effective way. Many Search Engines were introduced since 1990. In this paper we present a brief study on search engines. First, we present the definition of search engine, types of search engines and the general working process of a search engine. Then we give an example for the working process with a description of the Google search engine architecture. Later, we present a short description of the next generation search engines. Then we present comparisons among some major search engines. Index Terms— Internet; Search Engine; working; architecture. I. INTRODUCTION Access to various types of information is necessary these days. The World Wide Web (WWW) contains a lot of web pages. To search for the information necessary for us from that huge collection of web pages, using a Search Engine will provide with efficient results. Many web pages in the WWW contain inappropriate information. This is due to the inappropriate naming and unnecessary highlighting of the content of web pages by their web masters. This raises the need of a search engine. Using a good Search Engine will filter out the necessary and relevant information needed by the user. This paper presents an overview on the search engines. In the second section of this paper, we present the definition of search engine and we describe the types of search engines in the third section. We describe the general working of a search engine in the fourth section and present an example for it in the fifth section by explaining the Google search engine architecture. In the sixth section we present a brief explanation on the next generation search engines and in the seventh section we present comparisons among some major search engines. II. DEFINITION OF SEARCH ENGINE Definition 1: Search Engine is a program which searches the database, gathers and reports the information which contains the specified or related terms. Definition 2: The term Search Engine [11] refers to the process of searching files using the key words specified. The key words found are returned and collated into the user information. III.TYPES OF SEARCH ENGINES Search Engines are of four types[6]. They are Manuscript received Apr 18, 2011. Mr.K. Tarakeswar, Department of Computer Science and Engineering, G. Pulla Reddy Engineering College, Kurnool-518002, Andhra Pradesh, India. (e-mail : eshwartarak158@gmail.com) D. Kavitha, Department of Computer Science and Engineering,G. Pulla Reddy Engineering College, Kurnool-518002, Andhra Pradesh, India. (e-mail : dwaramkavithareddy@gmail.com) A.Crawler based search engines. B.Human powered directories. C.Hybrid search engines. D.Meta search engines. A. Crawler based Search Engines Crawler based search engines contain three parts. The first part is the ‘Crawler’ (bot or robot or spider). It is used to wander the web and create listings of web pages. The second part is the ‘Index’, which is a huge collection of copies of web pages and the third part is the ‘Search Engine Software’ which ranks the results. Because the crawler in this engine searches the web constantly, it provides updated information. Google, Live Search, Ask and most other search engines are crawler based. B. Human Powered Directories Human powered directories are search engines which depend on humans for their web page listings. These types of search engines get their listings of web pages from the submissions made by the respective web page masters. The submission contains the address, title and a brief description of the site. Later, the submission is reviewed by editors. A directory searches for results only from the page descriptions submitted to it. This is an advantage because, as the pages are submitted manually, the quality of the content will be better and more appropriate compared to the results retrieved by a crawler based search engine. But, the disadvantage is, any change made to an already submitted web page will not be updated until it is submitted again. Also, the ranking of pages can’t be changed once ranking is done. Yahoo, dmoz and Galaxy are some examples. C. Hybrid Search Engines Hybrid search engines include the features of crawler based search engines and human powered directories. Currently, some search engines are using both features to provide effective results. MSN, Google and Yahoo are some examples. D. Meta Search Engines Meta search engines fetch results from other search engines. The fetched results are combined and ranked again according to their relevancy. These search engines were useful when each search engine had a significantly unique index and search engines were less savvy. Because the search has improved a lot, the need for these has reduced. MetaCrawler and MSN Search are some examples. IV. WORKING OF SEARCH ENGINE The working [3], [4], [5] of Search Engine involves three basic tasks. They are, A.Searching the WWW and collecting the pages. B.Keeping the index of the words they find and where they were found. C.Allowing users to search for words or a combination of them from the index by using efficient software. Search Engines:A Study 1 Mr.K. Tarakeswar , 2 Ms. D. Kavitha 29