1. Physical label A physical label is a short sign used to indicate the name, weight, volume, purpose and other information of an item. There are traditional printed labels and modern bar code printed labels. Scope of application: packaging: shipping marks, postal parcels, letter packaging, transport goods labels, envelope address labels. Electrical appliances: mobile phone internal labels, various electrical labels, notebook computer labels, mechanical and electrical product labels. Commodities: price labels, product description labels, shelf labels, bar code labels, and drug labels. Management: book label, vehicle inspection label, security label, property label. Office: document labels, document preservation labels, various items and stationery labels. Production: raw material labels, processed product labels, finished product labels and inventory management labels. Chemical industry: labeling of paint materials, packaging labeling of gasoline engine oil products and labeling of various special solvent products. Others: anti-counterfeiting label [2], encryption label, anti-theft label. Jewelry: Jewelry tag, which is not easy to stick to goods. Clothing: clothing tag, washing label. Airport: boarding pass and luggage tag. Tickets: train tickets, coach tickets. Others: parking tickets, expressway toll tickets. 2. Network Tags (Tags) is a way of organizing Internet content and a keyword with strong relevance. It helps people to describe and classify content conveniently, so as to facilitate retrieval and sharing. Tags have become an important element of web 2.0. Tags delegate the right to organize content from webmasters to users, which fully embodies the bottom-up and user participation characteristics of web2.0. If you have visited web2.0 websites such as flickr (pictures), technorati (blogs) and del.icio.us (delicious bookmarks), you will find that websites use tags to display content, and users use tags to describe content and retrieve related content. The "open classification" used by Baidu Encyclopedia is also a manifestation of labels. 3. Electronic tags Electronic tags are also called radio frequency tags, transponders and data carriers; Readers are also called reading devices, scanners, reading heads, communicators and readers (depending on whether electronic tags can rewrite data wirelessly). Spatial (non-contact) coupling of radio frequency signals between the electronic tag and the reader is realized by coupling elements; In the coupling channel, energy transfer and data exchange are realized according to the time sequence relationship. Electronic tag is a tool to improve the efficiency and accuracy of identification, and this technology will completely replace bar code. Rfid radio frequency identification is a non-contact automatic identification technology, which can automatically identify the target object and obtain relevant data through radio frequency signals, and can work in various harsh environments without manual intervention. Rfid technology can identify high-speed moving objects and multiple tags at the same time, which is quick and convenient to operate. Rfid tag is a breakthrough technology: "First, it can identify a single very specific object, instead of only identifying one type of object like bar code;": Secondly, it uses radio frequency, which can read data through external materials, while barcode must rely on laser to read information; Third, multiple objects can be read at the same time, while barcodes can only be read one by one. In addition, the amount of information stored is also very large. "