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This type is reserved for edge devices that don't run Spanning Tree, such as computers, servers, and phones. An edge port skips over the learning state and transitions instantly to a forwarding state. RSTP still sends BPDUs on edge ports just in case there's a switch on the other end. But if it receives a BPDU, it will change the port type to a normal Spanning Tree port. If you're familiar with PortFast, this is essentially the same thing. In fact, IOS uses the portfast keyword to configure an edge port, as follows:

SW2(config)#int gi1/3 SW2(config-if)#spanning-tree portfast edge ? trunk Enable portfast edge on the interface even in trunk mode <cr> SW2(config-if)#spanning-tree portfast edge trunk %Warning: portfast should only be enabled on ports connected to a single host. Connecting hubs, concentrators, switches, bridges, etc... to this interface when portfast is enabled, can cause temporary bridging loops. Use with CAUTION

Keep in mind that an edge port can be an access port or a trunk port that's connected to multiple devices. If the port is a single-VLAN access port, you should use the spanning-tree portfast edge interface command. But if it's a trunked interface—such as one connected to a server running virtual machines or a computer plugged in behind an IP phone on a separate voice VLAN—you must use the spanning-tree portfast edge trunk interface command.