Very nice summary. As I looked over the document I did notice a few errors. Here are the corrections (in red) and few more notes to consider. Overall very nice.
STP is on by default on all Cisco switches and therefore is used all the time. I believe you mean CST? There are actually five types of STP that can be configured on Cisco switches, CST, PVST, PVST+ (default), RSTP and MST. PVST+ is the default and not RSTP. PVST+ is backward compatible with CST.
STP - Spanning-Tree Protocol prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging BPDU messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices.
CST - Common Spanning-Tree assumes one spanning-tree instance for the entire bridged network, regardless of the number of VLANs. This implementation reduces CPU load since only one Spanning Tree instance is maintained for the entire network. This implementation can be used when only one Layer 2 topology is needed in the network. This is specified in 802.1Q and is also known as the Traditional Spanning Tree Protocol. All CST BPDUs are sent over trunks using the native VLAN with untagged frames.
PVST - Per-VLAN Spanning Tree maintains a spanning tree instance for each VLAN configured in the network. It uses ISL Trunking and allows a VLAN trunk to be forwarding for some VLANs while blocking for other VLANs. Since PVST treats each VLAN as a separate network, it has the ability to load balance traffic (at layer-2) by forwarding some VLANs on one trunk and other Vlans on another trunk without causing a Spanning Tree loop. Cisco proprietary version of STP that offers more flexibility than the CST version. Per-VLAN Spanning Tree (PVST) operates a separate instance of STP for each individual VLAN. This allows the STP on each VLAN to be configured independently, offering better performance and tuning for specific conditions. The default when using ISL.
PVST+ - Per VLAN Spanning Tree Plus provides the same functionality as PVST using 802.1Q trunking technology rather than ISL. PVST+ is an enhancement to the 802.1Q specification and is not supported on non-Cisco devices. Cisco's second proprietary version of STP that allows devices to interoperate with both PVST and CST. Per-VLAN Spanning Tree Plus (PVST+) effectively supports three groups of STP operating in the same campus network: Catalyst switches running PVST, Catalyst switches running PVST+, and Switches running CST over 802.1Q. The default on most Cisco switches and when using 802.1Q.
RSTP - Rapid Spanning Tree Protocol (802.1W) is an evolution of the Spanning Tree Protocol (802.1D standard) and provides for faster spanning tree convergence after a topology change. The standard also includes features equivalent to Cisco PortFast, UplinkFast and BackboneFast for faster network reconvergence. Performs better than proprietary extensions of STP by Cisco without any additional configuration. Backward compatible with 802.1D or the traditional Spaning Tree protocol which uses CST.
MISTP or MST - Multiple Instance of Spanning Tree Protocol (802.1S) is an IEEE standard which allows several VLANs to be mapped to a reduced number of spanning-tree instances. This is possible since most networks do not need more than a few logical topologies. Each instance handles multiple VLANs that have the same Layer 2 topology. Combines the best of aspects from both PVST+ and 802.1Q. Relies heavily on RSTP and is more complex thas usual STP.
Portfast - Cisco proprietary enhancement to STP that ebables fast connectivity to be established on access layer switch ports connected to end workstations. In affect by passing the listening and learning states and going immediately to the forwarding state. STP loop detection is still operational and the port is put into a blocking state if a loop is detected. Disabled by default, but can be enabled either globally or on a per-port basis.
Uplinkfast - Cisco proprietary enhancement feature that improves convergence time in STP. Used on access-layer switches with blocked alternat port to the root switch. The Bridge priority is increased to 49152 and root path cost on ports is increased by 3000. Only reacts to a direct link failure on the access switch, meaning a port must physically go down to trigger the feature.
Backbonefast - Cisco proprietary enhancement feature that improves convergence time in STP. Configured on all switches in the network. Can save a switch up to 20 seconds (max age timer) when recovering from an indirect link failure. Not configured when RSTP is used, it is included and automatically enabled in RSTP.
Root Guard - Cisco proprietary enhancement to STP. Configured on a per-port basis and does not allow the port to become a RP, instead port is always DP. Should be configured on all ports where the root switch should not appear. Port functions normally unless a superior BPDU is received. Then the port is placed in a root-inconsistent state, no traffic passes through the port. Once the superior BPDU stops the port automatically recovers and transistions through the normal STP process (listening, learning and forwarding).
BPDU Guard - Cisco proprietary enhancement to STP. Used with the portfast feature. When the switch receives BPDUs on the port it is put in an err-disable state. Port must be manually re-enabled using the shutdowm, no shutdown command sequence.
Loop Guard - Cisco proprietary enhancement to STP that protects against the sudden loss of BPDUs. Used on no-designated ports to monitor incoming BPDUs. If there is a sudden loss of BPDUs then the port is put into a loop-inconsistent state. The port is basically blocking to prevent loops from forming and to keep the port in a non-designated role. Automatically recovers and becomes active again once BPDUs start flowing.
UDLD - Cisco proprietary enhancement to STP that interactively monitors a switch port to see whether the link is truly bi-directional. sends a special layer 2 UDLD frame at regular intervals and waits for an echo. If no echo is received then a failure must have occured. The goal is to detect a bidirectional failure (a unidirectional link condition) before STP has time to move a blocked port into a forwarding state. Two modes of operation;, normal mode and aggressive mode. Can be configured globally for all fiber-optic switch ports or on a per-port basis.
