Barcode is used to encode data for variety of purposes. 2D barcode can be used in e-governance applications to benefit the Government and the citizen at large. The 2D barcode is readable using mobile camera, web camera and scanners alike. As the mobiles have the GPRS/3G connectivity to Internet, the barcode encoded with the details of any ID card, driving license, ration card, certificate etc. can verify the details through the Internet. Thus anywhere, anytime service can be enabled to the citizen to know the status of the transaction. Barcode is meant for encoding data in an image which can commonly seen on the cover of all prod-ucts. Scanning of barcode with bar-code reader reveals the detailed information on particular product. Presence of barcode has eradicated the presence of counterfeit to a large extent. One dimensional bar-codes, which has been in use since mid 1970, a combination of bars and spaces, store data in a series of lines of various width. Each bar and space represent different character. Here the information are stored horizontally. Today the usage of 2D barcode is being exploited by the marketing segment and the manufacturing industry. 2D barcode can be effectively used as a low cost tool for knowing the current status of their request submitted to Government, eliminating forgery, locational information in open and secured way for variety of applications which touches Government, Enterprises, Business people and any citizen. Two dimensional barcodes are represented as a image with different geometric patterns such as squares, dots, and hexagons where storage happens both vertically and horizon-tally. Scanning and decoding of this type barcode needs 2D compatible scanner. 2D barcode technology should be considered as a comple-ment to traditional 1D scanning technology and not its replacement. One of the amazing aspects of two-dimensional symbols is their poten-tial durability. To sabotage the read-ability of a conventional 1D symbol, one only has to add another bar to the beginning or end of the symbol or draw a line through the symbol, parallel to the stripes. This throws off the checks and makes the symbol unreadable. By comparison, many degrees of redundancy can be built into a 2D symbol. While it makes the symbol somewhat larger, the remain-ing symbol is remarkably secure. Reports indicate that inspite of minor deliberate attempts on 2D symbols with holes, black marker and tearing, the symbol remains readable. Though there are so many symbol-ogies such as Maxicode, Aztec, Watercode, Minicode etc, 2D bar-codes with open standards are preferable for its reliability and inter-operability. Some of the examples for 2D Matrix symbologies of open stan-dard are detailed below. DataMatrix: DataMatrix is a 2D matrix code with modules arranged either in a square or rectangular pat-tern. The symbol consists of data regions which contain modules set out in a regular array. Each data region is delimited by a finder pat-tern, and this is surrounded on all four sides by a quiet zone border (margin). Each symbol has even number of rows and even number of columns. The size of square shaped symbols ranges from 10X10 to 144X144 and ranges from 8X18 to 16X48 for rectangular shaped sym-bols. Datamatrix 2D barcode ISO/IEC 16022:2006 specification can be obtained from http://datenfreihafen.org/projects/iec 16022.html (GPL) http://www.libdmtx.org/ (LGPL) PDF417: Developed in 1992 by sym-bol Technologies, PDF417 is a multi-row, variable length "stacked" symbol-ogy. It is composed with a stack of 3 to 90 rows. A PDF417 symbol consists of 17 modules arranged into four bars and four spaces. PDF417 uses Reed Solomon error correction. In order to recover the complete content of the document and genuineness, linear bar-codes such as PDF417 is widely used with encryption. The rectangular length and width of the barcode will increase based on the size of the encrypted data. The QR Code: The Quick Response Code (QR Code) is yet another 2D bar-code where the information stored can be a text, URL or other data. It is called as Quick Response Code because they enable fast data access. The symbol of QR code consists of black modules arranged in a square pattern. It also includes three levels of error detection. The squares in the bottom left, top left, and top right corners are locater patterns. QR Code ISO/IEC 18004:2006 spec-ifications can be obtained from http://www.iso.org/iso/iso_cata-logue/catalogue_tc/catalogue_detail.h tm?csnumber=43655 TWO DIMENSIONAL BARCODE USAGES The content that is encoded in the 2D barcode can vary depending on the requirement. It can contain an URL so that when read through mobile camera one can go online and reach the web-site to know more details. The content can be an offline content having the serial number, name card etc. details generally used in the manufacturing industry to identify the product, batch number etc. The content can have the latitude and longitude, the GPS coordi-nates to point a location. ONLINE METHODS The usage can be broadly classified into online and offline usages. Online methods contain either an URL or encrypted ID which can be read using the Javamidlet on mobiles or Client/Applet using a web camera. In case of mobiles the server can be reached through GPRS/3G and in case of Client/Applet using a web cam the server can be reached through LAN/WLAN/SWAN/broadband. In case of URL the browser becomes the client program to fetch the details and in case of encrypted-ID, there will be a client program/Applet to decode and connect to the server and give the nec-essary information. The encryption can be done in vari-ety of ways such as direct URL+ID, Direct URL+Encrypted ID, Encrypted ID, etc. Accessing rights also differs for each method. Few methods are open for the entire citizen, few for authenti-cated citizen, some only for depart-ment officials, etc. The verification devices to be used are mobile camera, Desktop/laptop connected with web camera, flat-bed scanner, and barcode reader. OFFLINE METHODS Print copy content authentication - Offline -- Manual method/Automated method are the different methods used here and the accessing rights goes to Closed User Group (CUG) of Department officials. The verification devices to be used are mobile camera, Desktop/laptop connected with web camera, flat-bed scanner, and barcode reader. Again offline methods contain the encoded information either with encryption or without encryption. Inventory slips, ID cards, Manufacturers details etc. are the know applications using the offline methods. The color 2D bar-code can be deployed for high capacity online and offline requirements. The color 2D barcode can have photos, images, digitally signed infor-mation etc. Color 2D Barcodes are also in existence for offline use. High Capacity Color Barcode (HCCBTM) which can have three times the density of PDF417/DM is used for high capacity requirement. APPLICATIONS OF 2D BARCODE TECHNOLOGY The applications such as land records, telephone connection, water connection, passport, ration card, election ID etc. can be encoded in the 2D barcode. Some of the applications implement-ed using 2D barcode with the support of NIC, Tamil Nadu are list-ed below. a) Kalaignar Vettu Vasathi Thittam Beneficiary identity: A secured encrypted ID is used as a 2D barcode to eliminate forgery of allotment orders of Government of Tamil Nadu. Here barcodes are encrypted so that no one other than department people can read it. b) E-district Citizen Certifi-cates: To eliminate forgery, a secured encrypted ID is used as a 2D barcode on certificates like Community, Nativity, No graduate, Income and Deserted woman. On reading the 2D barcode at left hand side of each certificate the user can trace out all the information about the citizen updat-ed earlier in the particular URL. c) Usage of 2D barcodes also benefited the Micro Small and Medium Enterprise department which deals with small scale industries, especially works on authenticity of license issued to the small scale entrepreneur. d) A proof of concept has been demonstrated to help the traffic police to identify the counterfeit license. The moment the traffic police scans the 2D barcode on a driving license the details dis-played from the server proves the authentication of the license. The application also facilitates to book an offense on the road using the mobile and the offense details are stored on the server for any time analysis/monitoring. Acknowledgement: K Sathyamoorthy, Junior Research Fellow, Tamil Nadu, k.sathyamoorthy@nic.in