A keyword, in the context of search engine optimization, is a particular word or phrase that describes the contents of a Web page. Keywords are intended to act as shortcuts that sum up an entire page. Keywords form part of a Web page’s metadata and help search engines match a page to with an appropriate search query.
A fourth generation (programming) language (4GL) is a grouping of programming languages that attempt to get closer than 3GLs to human language, form of thinking and conceptualization. 4GLs are designed to reduce the overall time, effort and cost of software development. The main domains and families of 4GLs are: database queries, report generators, data manipulation, analysis and reporting, screen painters and generators, GUI creators, mathematical optimization, web developmentand general purpose languages.Also known as a 4th generation language, a domain specific language, or a high productivity language.
4GLs are more programmer-friendly and enhance programming efficiency with usage of English-like words and phrases, and when appropriate, the use of icons, graphical interfaces and symbolical representations. The key to the realization of efficiency with 4GLs lies in an appropriate match between the tool and the application domain. Additionally, 4GLs have widened the population of professionals able to engage in software development. Many 4GLs are associated with databases and data processing, allowing the efficient development of business-oriented systems with languages that closely match the way domain experts formulate business rules and processing sequences. Many of such data-oriented 4GLs are based on the Structured Query Language (SQL), invented by IBM and subsequently adopted by ANSI and ISO as the standard language for managing structured data. Most 4GLs contain the ability to add 3GL-level code to introduce specific system logic into the 4GL program. The most ambitious 4GLs, also denoted as Fourth Generation Environments, attempt to produce entire systems from a design made in CASE tools and the additional specification of data structures, screens, reports and some specific logic.
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