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Freeware – These are the software which is available free of cost and which allows copying and further
distribution, but not modification. It is distributed in binary form without any licensing fee and source
code is not available. Ex. Adobe PDF, yahoo messenger etc

Open source software – It refers to software whose source code is available to customers and can be
modified and redistributed without any limitation. An OSS may come free of cost or with a payment of
nominal charges that its developers may charge in the name of development, support of software. Ex.
Open Office, Moodle, PHP etc

Free Software – Free software is software that can be freely used, modified, and redistributed with only
one restriction: any redistributed version of the software must be distributed with the original terms of
free use, modification, and distribution, no payments needed to be made.
Ex. Python, Perl, Linux, C/C++, PostgreSQL, Gimp, Apache, Mozilla etc

Network Security
Network offers endless possibilities and opportunities to every user of it, along with convenience, but
it’s not free of risk. For network security various security mechanisms are implemented. Some of them
are:
Authorization – It determines whether the service provider has granted access to the web service to
the requestor. In general it is confirmed by asking the login ID, if it is then a authorized user.
Authentication – It involves accepting credentials from the entity and validating them against an
authority. It is also known as password protection.
Encrypted Smart Cards – Passwords pass through the network in encrypted form. Hackers can
record it and can break it. A solution to the problem is encrypted smart card. . It generates a new
token every time that a computer system can recognize and if copied by some hacker, as next time a
new token is generated, so can’t be reused.
Biometric Systems – Most secure level of authorization, which involves some unique aspect of a
person’s body such as finger-prints, retinal patterns etc. to establish his/her identity.
Firewall – A system designed to prevent unauthorized access to or from a private network is called
firewall. Can be Implemented in both hardware and software or a combination of both.

COOKIES
Cookies are very small text files placed on a computer by a web server when a user view some sites
online (not all websites place cookies). Cookies stores user’s preferences so that a web server doesn't
have to repeatedly request this information, which makes download faster.
Cookies commonly stores personal registration data like user’s name, address, shopping cart details,
your preferred layout for a web page and some other choices.
Cookies make it easy for web servers to personalize information to fit user’s specific needs and
preferences when the user is visiting a web site, again.
There are three types of computer cookies:
• Session cookie(memorize your online activities e.g. online shopping)
• Persistent/first party cookie (work by tracking your online preferences e.g. login information,
language selections, menu preferences, internal bookmarks, and more)
• Third-party/Tracking cookie (collect data based on online behaviour which are then are then
passed on or sold to advertisers by the website that created the cookie. It stores info. like
interests, location, age, and search trends, used later for custom advertisements