Portals (or subject directories) are sites that organize resources on a subject, and may offer searching that focuses on the subject area.Often these portals are curated and maintained by members of university communities or library consortia, so unlike general search engines, these lists of links have been viewed and vetted by humans in the field of study. While you are bound to find many useful and relevant links through these portals, it is also possible that some links will lead to dead and/or unreliable pages.