Exclusive gateways are symbolized with this shape:
An exclusive gateway evaluates the state of the business process and—based on the condition—breaks the flow into one of the two or more mutually exclusive paths. Remember that the exclusive in "exclusive gateway" stands for mutually exclusive.
In the example below, an exclusive gateway requires that the mode of transportation be evaluated. In this case, one light will be placed in the Old North Church if the British attack by land; two if by sea.
Event-based gateways are symbolized with this shape:
An event-based gateway is similar to a exclusive gateway because both involve one path in the flow. In the case of an event-based gateway, however, you are evaluating which event has occurred, not which condition is being met.
An example of a event-based gateway is the decision to hold fire until your soldiers can see the whites of their enemies' eyes. In this process flow, if a certain amount of time passes without the British coming, the soldiers will go home.
Parallel gateways are symbolized with this shape:
A parallel gateway is very different than the previous gateways because you aren't evaluating any condition or event. Instead, parallel gateways are used to represent two concurrent tasks in a business flow. It is the same as a fork in a UML activity diagram.
In the example below, this business process uses a parallel gateway because the company is having its cake and eating it too.
Parallel event-based gateway
Parallel event-based gateways are symbolized with this shape:
As the name suggests, this gateway is similar to a parallel gateway. It allows for multiple processes to happen at the same time, but unlike the parallel gateway, the processes depend on specific events. You can think of a parallel event-based gateway as a non-exclusive, event-based gateway where multiple events can trigger multiple processes, but the processes are still dependent upon specific events.
Inclusive gateways are symbolized with this shape:
An inclusive gateway breaks the process flow into one or more flows. An example of a inclusive gateway is business actions taken based on survey results. In the example below, one process is triggered if the consumer is satisfied with product A. Another flow is triggered when the consumer indicates that they are satisfied with product B. A third process is triggered if they aren't satisfied with A. There will be a minimal flow of one and a max of two.
Complex gateways are symbolized with this shape:
As the name signifies, complex gateways are only used for the most complex flows in the business process. When possible, you should use a simpler gateway to do what needs to be done. If you need multiple gateways to describe the business flow, then that's an ideal case for the complex gateway. Complex gateways require more descriptive text because you're using words in place of symbols.