SEO glossary entries for numbers

200: HTTP Status code for success in retrieving a requested web page or resource.
301: HTTP Status code for a permanent redirect. Make sure that you use this if you want search engines to index pages that you are re-directing to.
302: HTTP Status code for Web page or web resource has been moved temporally.
400: HTTP Status code for a ‘Bad Request’, usually meaning that the syntax of the URL requested doesn't make sense. Perhaps the result of a typo in human-written URLs or a coding error in programmatically generated URLs.
404: HTTP Status code indicating that a web server could not find a web page or resource on a given URL.
500: HTTP Status code for an ‘internal error’, i.e. the server encountered an unexpected condition which prevented it from fulfilling the request. Indicating that there is some problem with your webserver's hardware or software configuration.
80/20 Rule: Synonym for ‘Pareto’s Principal’.