The Properties Bar is a vital part of the interface. It displays a list of all the settings you can change on whatever is selected. In the picture below, a layout is selected, so the layout's properties are showing.
There are too many properties in Construct 2 to list here. Instead, properties for different parts of the project are documented in the relevant manual section. For example, layout properties are defined in the Layout section.
Properties are organised in to categories which can be expanded and collapsed with the + button. There are many kinds of properties, including number fields, text fields, dropdown lists and clickable links. The property name appears in the left column, and the editable value appears in the right column.
Whenever something in the project is clicked or selected, its properties display in the Properties Bar. For example, selecting objects in the Layout View or clicking items in the Project Bar shows the relevant properties in the Properties Bar.
Things with properties
The following project elements have properties:
Many behaviors have their own properties - see the Behavior reference
Many plugins have their own properties - see the Plugin reference
Many objects also support effects and have properties for them as well.
See the relevant manual sections for documentation on the properties that are shown. There is also a Help link displayed at the bottom of the properties that will take you to a relevant manual section.
All properties also have a description which provide additional information about what the property is used for. This is displayed in a panel at the bottom of the Properties Bar. It is worth keeping an eye on this since it can contain useful hints and tips. An example is shown below.