What is the use of lightning:messages in salesforce lightning component?

Hi NIkita,

The severity attribute indicates a message's severity level and determines the style to use when displaying the message. If the closable attribute is set to true, the message can be dismissed by pressing the × symbol. To apply Lightning Design System styling, we recommend that you use lightning:notificationsLibrary instead of ui:message.

Ex:-

<aura:component access="global">
	<ui:message title="Confirmation" severity="confirm" closable="true">
			This is a confirmation message.
	</ui:message>
	<ui:message title="Information" severity="info" closable="true">
			This is a message.
	</ui:message>
	<ui:message title="Warning" severity="warning" closable="true">
			This is a warning.
	</ui:message>
	<ui:message title="Error" severity="error" closable="true">
			This is an error message.
	</ui:message>
	
</aura:component>