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Chapter 9

Glossary of Terms
E-mail address Determines message recipient and sender during communication using
the electronic mail.
HTTP Protocol for WWW pages transfer. By default, TCP protocol and port 80 is used.
HTTPS Securedversion of HTTP protocol. Securityis ensured by the encrypted protocol
SSL.
By default, TCP protocol and port 443 is used.
IMAP Clients can work with their e-mail messages on a server using IMAP. Messages
don’t need to be downloaded to local computer.
By default, TCP protocol and port 143 is used.
Packet Basic communication unit of network layer (i.e. independent of the communica-
tion medium). The IP protocol works on packet layer in TCP/IP.
POP3 Post Office Protocol enables users to download e-mail messages from a server to
their own local disc.
By default, TCP protocol and port 110 is used.
Port A port is a 16-bit number (the allowed range being 1 through 65535) used by
TCP and UDP protocols for identification of applications (services) on a particular
computer. Several applications may run at once (e.g. WWW server, e-mail client,
WWW client — browser, FTP client, etc.). Each application is uniquely determined by
itsport number. Ports1 through 65535 arereserved for standard or system use (e.g
80 = WWW). Ports above 1024 (inclusive) may be used by any application (typically as
a source port by a client or by a non-standard server application).
Protocol Formatspecification of transferred data and methods of their processing. Two
computers must use the same protocols to be able to communicate.
Majority of network protocols is standardized, so they can be used for a communi-
cation between devices from different vendors. Set of protocols used in the Internet
and known in general as TCP/IP can be used as an example.