Demonstration of one-way binding vs two-way binding

BoundVsUnbound.app

<aura:application >
    <aura:attribute name="demo" type="Boolean" default="{!true}" />
    <aura:if isTrue="{#v.demo}">
    	Unbound Set
        <aura:set attribute="else">
        	Unbound Unset
        </aura:set>
    </aura:if>
    <hr />
        <aura:if isTrue="{!v.demo}">
    	Bound Set
        <aura:set attribute="else">
        	Bound Unset
        </aura:set>
    </aura:if>
    <hr />
    <ui:button label="Toggle" press="{!c.toggle}" />
</aura:application>

BoundVsUnboundController.js

({
	toggle: function(component, event, helper) {
		component.set("v.demo", !component.get("v.demo"));
	}
})