Character	Uses
Apostrophe (')	segment terminator
Plus sign (+)	segment tag and data element separator
Colon (:)	component data element separator
Question mark (?)	Release character
Period (.)	decimal point.

The basic standardization concept of EDIFACT is that there are uniform message types called United Nations Standard Message. The message types have exactly one nickname consisting of six uppercase English alphabets. The message begins with UNH and with UNT.

Electronic data interchange architecture specifies four different layers namely
(i) Semantic layer
(ii) Standards translation layer
(iii) Transport layer
(iv) Physical layer

Phil Zimmermann developed PGP in 1991. It is a decentralized encryption program that provides cryptographic privacy and authentication for data communication. PGP encryption uses a serial combination of Hashing, data compresion, symmetric key cryptography and asymmetric key cryptography and works on the concept of "web of Trust" It is also called "Pretty Good Privacy".

Symmetric Key Encryption	ASymmetric Key Encryption
Same key is used for both encryption and decryption	Different keys is used for encryption and decryption
Speed of encryption or decryption is very fast	Speed of encryption or decryption is comparatively slow
Plain text and cipher text are of same size	The size of cipher text is always greater than plain text.
Algorithms like DES, AES, RC4 uses symmetric key encryption	Algorithms like RSA, ECC, DSA use asymmetric key encryption
The number of key used grows exponentially with the numbers of users	The number of key used grows linearly with the numbers of users
Provides confidentiality.	Provides confidentiality, authenticity and non- repudiation.

(i) Information leakage
(ii) Tampering
(iii) Payment frauds
(iv) Malicious code threats
(v) Distributed denial of service attacks
(vi) Cyber squatting
(vii) Typopiracy
(viii) Hacking

Stored value card is a type of debit card that is pre-loaded with certain amount(value), with which a payment is made. It is a card that has default monetary value onto it. The card may be disposed when the value is used, or recharged to use it again. The major advantage of stored value card is that customers don't need to have a bank account to get prepaid cards. There are two varieties for stored value card.
(i) Closed loop (single purpose) Eg: Chennai metro rail travel card.
(ii) Open loop (multipurpose) Eg.: Visa gift cards.

All Payment cards (including debit card) are usually plastic cards of size 85.60 mm width x 53.98 mm height, rounded corners with a radius of 2.88 mm to 3.48 mm and thickness of 0.76 mm. These standards dimensions are maintained universally in accordance with ISO/IEC 7810#ID-1.
(i) Publisher
(ii) Credit card number
(iii) Name of the card holder
(iv) EMV chip
(v) RFID symbol
(vi) Expiration month and year
(vii) Card brand logo
(viii) Magnetic stripe
(ix) Hologram
(x) Signature
(xi) CVC/CVV

(i) It is an online payment system designed to allow efficient and frequent payments of small amounts.
(ii) The majority of micro electronic payment system were designed to pay for simple goods on the Internet. e.g., subscriptions of online games, read journals, listen to a song or watch a movie online etc.
(iii) In general, the parties involved in the micro on-line payments are Customer, Service Provider and Payment processor.

Name-your own price websites are just like normal retail sites. In contrast, the buyer negotiates with the retailer for a particular product or service. https://in.hotels.com/

(i) The third wave is brought on by the mobile technologies.
(ii) It connects users for real-time and on-demand transactions via mobile technologies.
(iii) The term Web 3.0, summarize the various characteristics ofthe future Internet which include Artificial Intelligence, Semantic Web,Generic Database etc.

Organization related to open source:
(i)  Apache Software Foundation
(ii)  Free Software Foundation
(iii) Linux Foundation
(iv) Open Source Initiative.

(i) In this period of increased competition and cyber crimes, the computers used by indivudals or business organisations may have spy hardwares of rivals.
(ii) Open source hardware technology helps in such threats.
(iii) In this technique we get the components of the hardware and its circuit diagram, so that we can remove suspicious spyware if found.

(i) Free software is a concept developed in the 1980s by an MIT computer science researcher, Richard Stallman who defined four conditions, as outlined by the nonprofit Free Software Foundation.
(ii) These "four freedoms" emphasize the ability of users to use and enjoy software as they see fit.
(iii) Freeware usually refers to proprietary software that users can download at no cost, but whose source code cannot be changed.

There are two types of fibre optic cables available.
One is single-mode and another is Multimode.
(i) Single-mode cables are used for long distance transmission and at a high cost.
(ii) Multimode cables are used for short distance transmission at a very low cost.

(i) A cable interconnecting two devices directly is known as a null modem cable.
(ii) The crossover Ethernet cable is an example of the null modem cables.

(i) The RJ45 connector looks similar like a telephone jack but it looks a slightly wider. 
(ii) In RJ45 the "RJ" stands for the Registered Jack and the "45" simply refers to the interface standard.
(iii)The RJ45 connector is a small plastic cube. It has eight pins.
(iv) It is connected to each end of the Ethernet cable. It is also known as 8P8C connector.
(v) These plugs (connector) are inserted into Ethernet port of the network card.

SI.No.	Absolute URL	Relative URL
1.	Absolute URL is the complete address of a document on the Internet.	Relative URL is the partial address of a document on the Internet.
2.	Absolute URL contains all the information that are required to find the files on the Internet.	Relative URL contains only file name or file name with folder name.
3.	If any of the four parts is missing, then the browser will not be able to link to the specific file. So, all the four parts are very important in absolute URL.	We can use this type of URL when the file is on the same server related to current document.

No.	IPv4	IPv6
1.	IPv4 address is a 32 bit unique address given to a computer system.	IPv6 address is a 128 bit unique address given to a computer system.
2.	There are two ways to represent the IP address: Binary notation, Dotted-decimal notation.	It follows Hexadecimal number notation.
3.	The number of address that can be formed is 232.	The number of addresses formed in IPv6 is 2128

(i) Group information sharing over long distances.
(ii) Broadcast announcements.
(iii) Fostering diversity of thought.

Cloud storage
1. It is just storage of data on online, access in different area no geographical limits was in need.
2. Cloud storage provides users with immediate access to a broad range of resources.
Cloud computing:
1. It is the on demand availability of computer system resources.
2. Especially data storage and computing power, without direct active management by the user

Database Connections: Accessing MySQL Database, connect to Database Server machine via PHP scripting language using Mysqli_connect() Function.
Syntax:
mysqli_connect("Server Name","User Name","Password","DB Name");
This function requires four parameters to connect to database server. Database Server name, Database username, password and Database Name.

mysqli_affected rows( )	mysqli_fetch_assoc( )
It returns the number of affected rows in the prearvious SELECT, INSERT  UPDATE, REPLACE, or DELETE query.	It fetches a result rowas an associative aray
Return value: An integer >0 indicates the  number of rows affected (0 indicates that no records were affected. '-1' indicates that the query returned an error).	Returns an associative array of strings representing the fetched row. NULL if there are no more rows in result set.
Syntax: mysqli_affected_rows (connection);	Syntax: mysqli fetch_as-soc(result);

File handling is needed for any web application development process. File handling in PHP similar as file handling is done by Clanguage. PHP has many functions to work with normal files.

Associate array	Multidimensional array
Associative arrays are arrays that use named keys that you assign to them.	An array containing one or more arrays.
It storing data in a liner	Multi-dimensional arrays that are two, three, four, five, or more levels deep.
We can associate the name with each array element in PHP using = > symbol.	It can be represented in the form of a matrix which is represented by row * column.