Cell phone NFC and Bluetooth has now been very widely used, the principle is the radio transmission technology, but they have a fundamental difference.

IMEI code, namely the serial number of the mobile phone. It is the abbreviation of International Mobile Equipment Identity. Like the identity card of a mobile phone, it is used to help identify the identity of a mobile phone. Each mobile phone has only one serial number, which is not the same. We usually match the serial number displayed after pressing the "* # 06 #" key on the mobile phone with the barcode on the mobile phone box and the serial number in the back of the mobile phone after removing the electric board. If the three are the same, it is more likely to be genuine goods (not excluding second-hand goods).

Subnet mask is also called network mask, address mask and subnet mask. It is used to indicate which bits of an IP address identify the subnet where the host is located and which bits identify the bit mask of the host. The subnet mask cannot exist alone. It must be used in combination with the IP address. The subnet mask has only one function, which is to divide an IP address into two parts: network address and host address. The subnet mask is the basic knowledge that everyone who uses the Internet must master. Only by mastering it can you truly understand the TCP/IP protocol settings. Let's explain what subnet mask is in simple terms.

Discrete graphics card refers to a graphics card that exists as an independent board and needs to be inserted into the corresponding interface on the motherboard. Discrete graphics card has independent video memory, does not occupy system memory, and is technically ahead of integrated graphics card, which can provide better display effect and operating performance. Discrete graphics cards are divided into built-in discrete graphics cards and external graphics cards. As an important part of the computer host, the graphics card is very important for those who like to play games and engage in professional graphic design. At present, the suppliers of graphics chips for civilian graphics cards mainly include AMD (formerly ATI) and nVIDIA.

iCloud as a cloud service provided by Apple, users can get 5GB of cloud space for free, if more than 5GB of space we need to buy space, then there is no other way to solve it?