By default, every task generated by a workflow will wait until that task is completed (or skipped) before creating the next task in the workflow.
Sometimes however, you will want to see what's coming next (especially if multiple steps can be done in any order). This is where Wait Steps and Non-Wait Steps come in.
Editing Wait Steps in your Process
The default, when you add a step to a workflow, is for that step to be a wait step (no other steps will be generated until that step is completed).
To change this on a step, click on the hand icon on the right side of the step.
When the hand icon is blue, the step is a wait step.
When the hand icon is gray, the step is not a wait step. This means that the next step in the workflow after the non-wait step will also be created. If it is also a non-wait step, the next step after it will also be generated; all the way up to the next wait step.
Now, go through your process and decide if you want to make any of the steps non-wait steps!