2. Search engine
• A web searchengine is a software system thatis designed to
search for informationon theWorld Wide Web. The search
results are generally presented in a lineof results often referred
to as search engineresults pages (SERPs). The informationmay
be a mix ofweb pages, images, and other types of files. Some
search engines alsominedata available in databases or open
directories. Unlike web directories, which are maintainedonly
by humaneditors, search enginesalso maintainreal-
timeinformationby runningan algorithm on a web crawler.
4. • A social networkis a social structure made up of a set
of social actors (such as individuals or organizations) and a set
of thedyadic ties betweentheseactors. The social network
perspective provides a set of methodsfor analyzing the
structure of whole social entitiesas well as a variety of
theories explainingthepatterns observed in these
structures.Thestudy of thesestructures uses social network
analysis to identify local and global patterns, locate influential
entities,and examine network dynamics.
Social network
6. email
• Electronic mail, most commonly referred to as email or e-
mail since ca.1993,[2] is a method of exchanging digital messages from an
author to one or more recipients. Modern email operates across
the Internet or other computer networks. Some early email systems required
that the author and the recipient both be online at the same time, in
common with instant messaging. Today's email systems are based on
a store-and-forward model. Emailservers accept, forward, deliver, and store
messages. Neither the users nor their computers are required to be online
simultaneously; they need connect only briefly, typically to a mail server, for
as long as it takes to send or receive messages.
• Historically, the term electronicmailwas used generically for any electronic
document transmission. For example, several writers in the early 1970s
used the term to describe faxdocument transmission.[3][4] As a result, it is
difficult to find the first citation for the use of the term with the more specific
meaning it has today.
