What is the use of ltng:outApp in Lightning Application in Salesforce?

ltng:outApp: – Extending from ltng:outApp adds SLDS resources to the page to allow your Lightning components to be styled with the Salesforce Lightning Design System (SLDS). If you don’t want SLDS resources added to the page, extend from ltng:outAppUnstyled instead.

The ltng:outApp component is a special type of Lightning application that is used to specify the dependencies for a Lightning Out app or a Lightning Components for Visualforce app. It allows you to use your Lightning components outside the Salesforce Lightning Experience, such as in a standalone web page or a Visualforce page https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/lightning_out_dependencies soccer skills world cup