What is aura:attribute in Salesforce?

They are same as member variable in apex classes, they are typed fields and are instance of a component. Attribute helps in making component more dynamic.

All attributes have a name and a type can be marked required by specifying ‘required=true’and can also have a default value. It has a naming rule as well:

1. Must begin with a letter or an underscore
2. Must contain only alphanumeric or underscore characters

Hi,

Attributes are named parameters in your component that you can display, manipulate and otherwise interact with throughout the component.

In your Developer Console, navigate to New > Lightning Component, and create a new bundle named abcComponent2. Add the following code and save.

<aura:component >
<aura:attribute name="greeting" type="String" default="Hello!" />
<h1>Component 2 - Attributes</h1>
<p>{!v.greeting} from Aura.</p>
</aura:component>

You’ll notice that the attribute is called “greeting” and that the expression {!v.greeting} also refers to “greeting”. The {!something} syntax is likely familiar to anyone who’s worked in Visualforce. The v in {!v.something} represents the “view”. So one way to think of how this component works is that the <aura:attribute /> tag puts a field on the view with a default value, and the {!v.something} pulls the value of the field out of the view and does something with it.