hypermedia, search, search engines, boolean search, boolean operators. AND, NOT, OR
Data is retrieved from a hypermedia (internet, web site, intranet) using a search engine which is different to an SQL Query on a database.
Search engines are used to search web sites by using keywords. The search engines will look for keywords amongst the meta tags on a web site. Meta tags are lists of words included on a page but not displayed which are designed to help these search engines locate a page. A search engine will only search for sites that are located in its index. The index is created by submitting your site to a particular search engine or by being picked up when the search engines do a a scan to update its search engine. Web crawlers or spiders are used to build the database. Web crawlers and spiders are programs that are designed to search the web and send the information back to the index. Searches carried out by web crawlers are going to be much slower and less efficient as they will inevitably come up with thousands of entries for most searches. For most users this is entirely unworkable. As such the search Engines of companies such as Yahoo have grown enormously as people depend more and more upon the searches which they have already carried out and sorted. This saves huge amounts of time. More advanced Searches can be carried out by using advanced search engines such as “Google” and “Dogpile”. These advanced search engines can also be further refined by using logical operators to further define the criteria.
Companies such as Yahoo also offer directories of categories such as Sport or entertainment to help browsing.
A search robot is a program that accesses web sites and gathers information for search engine indexes. It will ask each of the servers which programs should be included and which excluded. It does not go through firewalls.
Search engines use Boolean Operators to find what they want. The Boolean operators are AND, NOT, and OR. See operators under Searching in the Information Systems menu
Related Topics: DBMS, The 5 Types of Information Systems, Expert Systems, TPS, DSS, ES, MIS, OAS, Characteristics, computerised methods, non-computerised methods, flat file databases, relational databases, data modelling, URLs, storyboards, searching, HTML, backups, security methods, encryption, firewalls, virus' and virus scanners, passwords and security levels, social and ethical issues, data accuracy, data integrity, data validation, data bias, data reliability, privacy, ownership and control of data, access to data, data warehousing, data mining, freedom of information, acknowledgement of data sources, issues related to new trends, sequential access, direct access, distributed databases, storage media, querying, operators, wildcards, sorting, SQL, biometrics and ethical issues, face recognition , information systems trivia