What is a URL?


A URL usually refers to the address of a web page on the Internet. Enterprises and institutions or individuals use technical processing to store some information on the Internet in a page-by-page manner. Each page has a corresponding address for other users to access and obtain information. Such addresses are called web addresses. Web address In the Internet, if you want to access another computer on the Internet from one computer, you must know the address of the other party. The URL mentioned here actually refers to two meanings, namely IP address and domain name address. On the surface, these two words are quite professional, but as long as you explain them, you will understand the truth.


A computer is a digital world. Any information is represented in a digital form in the computer. Even if a person's name is represented in the computer, there is a corresponding digital code corresponding to it. In the networked world, in order to accurately find the destination computer, each computer must be marked with a unique address. Just as you have to know the other person's phone number to make a call, this number must be unique. Generally, this address is represented by four decimal (that is, IPv4) numbers, separated by a decimal point in the middle, and is called an IP address. IP is an abbreviation of Internet Protocol. [1] 
However, for human beings, it is difficult to remember a computer website represented by numbers, not to mention tens of millions of IP addresses on the Internet. In order to solve this problem, people use computer-friendly names to represent computers. In order to ensure the uniqueness of the computer identification on the Internet, a scheme can adopt a centralized naming and management approach. There is only one agency on the Internet responsible for this work. Obviously, this scheme is not realistic. So the Internet specifies a set of naming mechanisms called the Domain Name System. A website name using a domain name system is a domain name address. The domain name address is expressed hierarchically, China is cn, the United States is us, the server category is on the far left, and www indicates that this computer is a Web server.
Understanding URLs is the basis for Internet users to access the Internet. In practical applications, IP addresses and domain names are widely used.

Category editor
A URL usually refers to the address of a web page on the Internet. The Internet address is an important identifier of the Internet. You must enter the Internet address to browse network information and run network application software. Internet URLs vary with the content of the application. The IP address or domain name is used to access the server; the email address is used to send and receive email; and the file address is used to access files on the network.


IP address editing
There are many complex networks and many different types of computers in the Internet. Connecting them and communicating with each other depends on the TCP / IP protocol. According to this protocol, every computer connected to the Internet must have a unique address identifier. This address is called an IP address. An IP address is a number that indicates the location of a computer on the Internet. IP addresses are unique, that is, different computers connected to the Internet cannot have the same IP address. Because IP address resources are very limited, generally only special servers have fixed IP addresses, and users who dial-up or broadband Internet access are basically dynamically assigned a temporary IP address by an ISP.
Disadvantages of IP addresses:
A digital IP address is not easy for users to remember and use, and the name or nature of the organization owning the address cannot be seen from the IP address, and the IP address cannot be determined based on the company or organization name or organization type. [2] 
The network system actually only recognizes the IP address. When the domain name is entered, the domain name system in the network will automatically convert the domain name into the corresponding IP address, so that the host can be found and accessed based on the address. The IP address is equivalent to the house number of the location of each computer in the network. For example, every building in the street has a unique house address. The domain name is equivalent to the name of the building. Buildings on the street have house numbers, but they should not have names. Every computer on the network has a unique IP address, but not necessarily a domain name

Domain Editing
Because IP addresses have the disadvantages of being inconvenient to remember and failing to display the name and nature of the address organization, people have designed the name of a computer or computer group on the Internet consisting of a string of dot-separated names. This is the domain name. [2] 
The URL consists of two or more words, separated by periods. The word on the far right is called the top-level domain. Here are a few common top-level domains and their usage: * .COM--for commercial organizations. It is the most common top-level domain. Anyone can register a .COM domain name. * .NET-Originally used for network organizations, such as Internet service providers and maintenance. Anyone today can register a domain name that ends in .NET. * .ORG-is for various organizations including non-profit organizations. Today, anyone can register a domain name that ends in .ORG.
Top-level domains are divided into two categories:
First, national top-level domain names (nTLDs). More than 200 countries have assigned top-level domain names according to the ISO3166 country code. For example, China is cn, the United States is us, and Japan is jp.
The second is international top-level domain names (iTDs), such as .Com for industrial and commercial enterprises, .net for network providers, and .org for non-profit organizations. Most domain name disputes occur under the top-level domain name of com, because most companies go online for profit. In order to strengthen the management of domain names and resolve the tension of domain name resources, international organizations such as the Internet Association, Internet Addressing Agency, and the World Intellectual Property Organization (WIPO) have extensively negotiated. Based on the original three international gTLDs: (com), the new Added 7 international top-level domain names: firm (company company), store (sales company or enterprise), Web (unit highlighting WWW activities), arts (unit highlighting cultural and entertainment activities), rec (highlighting recreational and entertainment activities Units), info (units that provide information services), nom (individuals), and choose new registries worldwide to accept domain name registration applications.
Domain names are generally represented by easy-to-understand abbreviations, and at the same time, they can directly reflect the hierarchical management method. [2] 
Its format is as follows:
www. <user name> <second-level domain name> <first-level domain name> [2]
1. Second-level domain name
The second-level domain name refers to the domain name under the top-level domain name. Under the international top-level domain name, it refers to the online name of the domain name registrant, such as ibm, yahoo, microsoft, etc .; Under the national top-level domain name, it is a symbol representing the category of registered enterprises , Such as com, edu, gov, net, etc.
The top-level domain name officially registered and operated by China in the Inter NIC is China, which is also the first-level domain name in China. Under top-level domain names, China's second-level domain names are divided into category domain names and administrative area names. There are 6 categories of domain names, including ac for scientific research institutions; com for industrial and commercial financial enterprises; edu for educational institutions; gov for government agencies; net for internet information center and operation center; Org for non-profit organizations. There are 34 administrative regions, which correspond to Chinese provinces, autonomous regions and municipalities.
2. Third-level domain names
Third-level domain names are composed of letters (A ~ Z, a ~ z, upper and lower case, etc.), numbers (0-9), and connectors (-). Real-level dots are used to connect domain names at all levels. The length cannot exceed 20 characters. If there is no special reason, it is recommended to use the applicant's English name (or abbreviation) or Chinese Pinyin name (or abbreviation) as the third-level domain name to maintain the clarity and conciseness of the domain name.
Development History
In 1985, Symbolics registered the first .com domain name. At that time, domain name registration was just emerging, and few applicants.
In 1993, the WWW agreement appeared on the Internet, and domain names began to catch on.
In 1993, Network Solutions (NSI) signed a five-year contract with the United States Government to exclusively represent the registration rights of three international top-level domain names, .COM, .ORG, and .NET. At that time, the total number of domain names was only about 7,000.
Domain registration
1. For domain names with websites. (Domains without a website need not be registered)
2. Refers to the relevant information submitted to the website by the Ministry of Information Industry.
The purpose of domain name registration is to prevent illegal website operation activities on the Internet and to combat the spread of bad Internet information. If the website is not registered, it may be shut down after being investigated. After the domain name registration application is successfully completed, the customer service will take the initiative to register the domain name. The domain name registration review time is generally about 7 working days. After successful review, you can access normally. In accordance with the spirit of the "Administrative Measures for the Recording of Non-operating Internet Information Services" reviewed and approved by the Twelfth Ministerial Conference of the Ministry of Information Industry of the People's Republic of China, the provision of non-operating Internet information services within the territory of the People's Republic of China should be filed! Without filing, they shall not engage in non-operational Internet information services within the territory of the People's Republic of China. The unregistered website will be fined or closed. Filing is to report to the competent authority for the record. From the perspective of administrative law, the record is mainly in practice the provisions of the Legislative Law and the Regulations on Records of Regulations.
Application Guide
When applying for domain name registration, applicants can submit domain name registration application forms to domain name registrars through domain name registration inquiry online registration, email, etc., and submit domain name registration applications, and sign domain name registration agreements with domain name registrars.
The domain name registration application form should include:
1. The applied domain name;
2. Host names and IP addresses of the primary and secondary DNS servers;
3. The name of the domain name holder, the person in charge of the unit, the industry of the unit, the correspondence address, zip code, email, phone number, fax number, and authentication information;
4, domain name technical contact, management contact, payment contact, the name of the organizer, the name of the unit, correspondence address, postal code, e-mail address, telephone number and fax number.
The format of an English domain name is as follows: The domain name is formed by any combination of specific character sets, English letters, numbers, and "-" (that is, hyphen or minus sign) in each country's language, but it cannot contain "-" at the beginning and end. The letters in the domain name are not case sensitive.
The maximum length of a domain name can be 63 characters. Because the domain name suffix may be a two-letter country domain name or a new top-level domain name consisting of multiple letters, the longest definition of a domain name is usually limited to second-level domain names, that is, www and top-level Domain names such as those between .com [3].
The format of Chinese domain names is as follows: The length of domain names at all levels is limited to 26 legal characters (Chinese characters, English a-z, A-Z, numbers 0-9 and-are counted as one character); they cannot be pure English or numeric domain names, and there should be at least one Chinese character. "-" Cannot appear continuously.
The registration of domain names follows the principle of first application first registration, and the management agency does not conduct any substantive examination on whether the domain name proposed by the applicant violates the rights of third parties. At the same time, each domain name registration query is unique and non-repeatable. Therefore, on the Internet, the domain name is a relatively limited resource, and its value will gradually be valued by people with the increase of registered enterprises.
English name: DNS (domain name resolution) How can I see the contents of my website after registering a domain name? In a technical term, it is called "domain name resolution". As explained in the explanation of related terms, the domain name and the URL are not the same thing. After the domain name is registered, it only indicates that you have the right to use the domain name. If the domain name is not resolved, then the domain name cannot play its role. The resolved domain name can be used as the suffix of the e-mail address, or it can be used as the URL to access your own website. Therefore, the necessary link for the domain name to be used is "domain name resolution". We know that the domain name is a set of address conversion systems specially established for the convenience of memory. To access a server on the Internet, you must finally achieve it through an IP address. Domain name resolution is the process of re-converting a domain name to an IP address. A domain name can only correspond to one IP address, and multiple domain names can be resolved to one IP address at the same time. Domain name resolution needs to be done by a dedicated domain name resolution server (DNS).
Network file address editing
All data information on the network, including text messages and application software, are considered network files. In order to facilitate searching, each network file has a unique address, and the format of the network file address representation

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