Achievements allow you to set specific targets to users.
Goals are a way to set objectives for someone to work towards. Each goal can be broken down into smaller sets of targets, and each target can have an achievement attached to it in order to make it specific.
When adding a target to a goal you then have the option to add achievement which will give you a further set of options to choose from.
What do you want to achieve
This displays a list of all of the event types which the the owner can have on their timeline. Selecting one or more from this list means that these will be the types of event which the user should be linking to this goal in order to demonstrate progress against it.
How many do you want to complete
This is the number of different events that the user should link in order for this target to be considered complete.
How would you like to record progress
Here you can choose for events to be automatically linked every time they are created onto the user's timeline, or for the user to have to manually link when creating new events.
With automatic linking every time events of this type are created they are automatically linked to this target. Confirmation that this linking is occurring is displayed within the link to goals popup on the create screen for a new event. It is always possible for users to deselect these links from this popup when creating the event if they wish.