WiFi and WLAN

Most modern WLANs are based on IEEE 802.11 standards and are marketed under the Wi-Fi brand name.

WiFi Education

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WLAN

WLAN 工作在 OSI 的层一和层二，即 Physical layer （PHY）and Data Link layer（MAC & LLC）。如果你熟悉 wired network，如 Ethernet，对照了解即可。

A wireless local area network (WLAN) is a wireless computer network that links two or more devices using a wireless distribution method (often spread-spectrum or OFDM radio) within a limited area such as a home, school, computer laboratory, or office building.

Wi-Fi

简单地说，Wi-Fi 是 WLAN 的一个具体实现技术，基于 802.11 标准，致力于业界产品互操作性的测试和认证，Wi-Fi 商标由 Wi-Fi 联盟拥有。追溯起来，Wi-Fi 不是什么缩写，就是选出的一个 名字。

Wi-Fi is a trademark of Wi-Fi Alliance. It is actually not a standard and only ensures that products using this trademark can interoperate with each other. As most Wi-Fi products use the IEEE 802.11b standard, Wi-Fi usually refers to 802.11b. Wi-Fi is a new technology that uses the WLAN protocol.

Wi-Fi can provide wireless coverage in an area with a radius of up to 90 m (300 inches), while the WLAN can provide wireless coverage in an area with a radius 5 km (with antennas used). The biggest advantage of Wi-Fi is its high transmission speed (up to 11 Mbit/s). Wi-Fi is a short-distance wireless transmission technology applicable to offices and households.

Wi-Fi

Hotspot (Wi-Fi)

A hotspot is a physical location where people may obtain Internet access, typically using Wi-Fi technology, via a wireless local area network (WLAN) using a router connected to an internet service provider.

• Apple OS 7 以上，通过 Personal Hotspot 可以对外共享 3G/4G 互联网连接，这是以软件实现的 Wi-Fi 热点（Software hotspots）。

Wi-Fi、Access Point and Hotspot

Wi-Fi is the technology. You build a wireless network based on the Wi-Fi specifications and principles.

An Access Point is a physical device which is used to offer Wi-Fi service to a small area.

A Hotspot is the area served by an access point.

So, you go to a hotspot so you can connect with an access point using Wi-Fi.

Hotspot is the where, access point is the what, Wi-Fi is the how.

Wi-Fi and Internet 示意

Wi-Fi and Internet

Residential gateway

简单的一个应用场景就是你家的家用网关，也能了解到不少知识。