The document summarizes the history and uses of computer networks. It began in the 1950s with the idea of transferring data, which was first demonstrated between computers at UCLA in 1969. Computer networks allow users to access programs and data across multiple devices, share peripherals like printers, communicate via email, backup information, and enable teleconferencing. There are two main types of networks: local area networks (LANs) which connect computers within a small geographic area using high-capacity, low-error connections; and wide area networks (WANs) which connect LANs across a wider area using lower capacity links with a higher bit error rate.

1. By
Md.Ariful Islam
&
Md. Kausarul Alam Shuvo
Dept. of Computer Science &
Engineering
Jatiya Kabi Kazi Nazrul Islam
University

3.  The computer network was first use in 1950’s
decades . The idea of transferring data came
out at 1961 . Then the period of time it became
more developed . In 1969 University of
California , Los Angeles ( UCLA ) first
transferred data by using the computer
network .

5.  1. We can access programs and data from more
than one computer at the same time .
 2. We can sharing peripheral devices like
printers , scanners etc .
 3. Personal communications like E-mail .
 4. Making backup of information .
 5. Aiding communication by teleconferencing and
video-conferencing .
 6. Protecting information by account name and
password .
 And many other purposes .

6.  1. Local Area Networks (LANs)
2. Wide Area Networks (WANs)

7.  The major characteristics of LANs are given
below :
Multiple computers are connected together .
Computers are spread over a small geo-
graphical area .
Channels are of high capacity (Mbps , Gbps) .
Channels are relatively error free
(generally 1 error in 1,000,000,000 bits)

8. Network
operating
system
Other
Network
Network
Gateway
printer
Server
PC PC
PC
PC
Figure : A local area network .

9.  The special characteristics of WANs are
given below :
Multiple computers are connected together .
Computers are spread over a wide geo-
graphical area .
A WAN usually interconnects multiple
LANs
Links are of low capacity (low data rate) .
Bit error rate is higher than LAN (1 in 100,000) .

10. WAN
LAN
LANLAN
LAN
Individual
Computer
Figure : A wide area network .