Anything inside the {! } or {# } delimiters is evaluated and replaced when the component is rendered or when it uses the value. Unbound attributes are designated by {# } and do not update if the underlying object or attribute has changed. Unbound Attribute Example: Child Component <aura:component>     <aura:attribute name=”childAttr” type=”String” /> … Continue reading {! } and {# } delimiters in Salesforce Lightning