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USB A. The classic, widely accepted USB port, which has recently been losing ground to the more advanced USB C port.
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USB C. This connector differs from the classic, full-size USB by its much smaller size and its reversible design, which allows the plug to be inserted either way. This interface is rarely found in desktop PCs but is becoming more popular in laptops, tablets, and phones. Note that the Type C standard only describes the connector's design; the USB version (interface) is described in the section below.
The main difference between interface versions is bandwidth — or speed.
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USB 2.0. The outdated version 2.0 provides data transfer speeds up to 480 Mbps. It is found only in USB A ports.
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USB 5Gbps (3.2 gen1). Previously known as USB 3.1 gen1 and USB 3.0 (quite the confusion). Unlike 2.0, this version provides 10 times higher maximum speed (4.8 Gbps) and more power supply capability, enabling the connection of energy-intensive devices and extensive hubs.
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USB 10Gbps (3.2 gen2). A further improvement on the USB 3.2 gen1 standard (and as usual, its previous names USB 3.1 gen1 and simply USB 3.1), achieving a maximum speed of 10 Gbps and even higher power supply for external devices.
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USB 20Gbps (3.2 gen2x2). As the name suggests, this interface supports speeds up to 20 Gbps.
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USB4 40Gbps / Thunderbolt 4. Connecting a USB4 or Thunderbolt 4 hub to a PC allows simultaneous data transfer at speeds up to 40 Gbps via a single cable, connecting multiple monitors (e.g., two 4K or one 8K display), using high-speed storage with PCIe, providing device power up to 100 W, and connecting peripherals such as network cards, audio interfaces, and chargers, turning a single USB-C port into a multifunctional docking station.
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Lightning. Apple's proprietary interface used in its compact devices (iPhone, iPad, and iPod touch) since 2012. Application-wise, it is fully analogous to the microUSB described above, with the adjustment that it is only found in Apple gadgets and not used by other manufacturers.
— Internal USB. A variety of the USB standard used for connecting internal card readers (see "Type," "Purpose"). It differs from external USB by the connector; a card reader with such a connection can only be connected to connectors on the motherboard and is incompatible with external USB ports. Other characteristics are fully similar to the corresponding external USB standard (see above).
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microUSB. A smaller version of the external USB interface (see above): the size of such a connector is many times smaller than the full-size one, making it suitable for use in portable equipment, particularly smartphones and tablets. In fact, it is usually on such equipment that card readers and hubs are designed to be used with this interface. Note that normal operation is only possible if the main device can operate in USB host mode (this function is called USB On-the-Go).
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Wi-Fi. A wireless standard originally developed as a network-building technology; later the Wi-Fi Direct technology appeared, allowing devices to connect directly to each other. In card readers and hubs, this technology is chiefly found among models designed for use with mobile devices (laptops, smartphones, tablets) that have a built-in Wi-Fi module. The advantage over wired interfaces is not only the absence of cables and corresponding freedom of movement but also the capability of connecting multiple devices simultaneously and exchanging data with them. Some Wi-Fi models can even be connected to computer networks as full-fledged network storage. The drawback is the need for its own power source — either connection to the network, accordingly limiting freedom of movement, or a battery that has a limited autonomous operation period (within several hours).
— ExpressCard. A compact peripheral connection standard primarily used in laptops. ExpressCard devices usually measure 75x34x5 mm and fit into a special slot in the computer's body. Depending on system specifics, it can provide speeds up to 2.5 Gbps, but overall is less universal and convenient than USB, which explains its significantly lower prevalence and ongoing loss of popularity. Found exclusively in card readers (see "Type").
— Proprietary connector. Connecting external card readers (see "Purpose") through an original connector, generally used in a particular manufacturer's equipment and not aligning with common standards like USB (see above). The application of such models is fairly limited; they are often released as additional accessories for specific models of portable equipment (e.g., tablets).
The main material used for the body of the device.
— Plastic. Plastic is light, cheap, quite practical, incl. has good strength properties. In addition, it allows you to create cases of complex shape and almost any color.
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Metal. As a rule, aluminium-based alloys are used for metal cases. Such cases are much stronger than plastic ones, and also have a stylish appearance. On the other hand, in terms of impact protection, this material has no advantages over plastic, but it costs more, and it can weigh much more.
