An salesforce app is a set of objects, fields, and other functionalities that supports a business process. It is a group of tabs that works as a unit to provide the application’s functionality. It consists of a name, a logo, and an ordered set of tabs. The simple app contains only one tab.
There are two types of Apps in Salesforce:
Standard Apps
Standard apps come with every instance of Salesforce by default. It includes App Launcher, Call Centre, Community, Content, Marketing, Sales, Salesforce Chatter and Site.com. You can customize the standard apps based on the requirement of an organization. The change of the label, description, and logo is restricted.
Custom Apps
Custom apps are built to meet the specific business needs & requirements of an organization. Custom apps are made by grouping standard as well as custom tabs. Logos in custom apps can be added and they can be changed after that also.
To create a custom app, you need to follow the path
Setup -> App Manager -> New Lightning App
Main Fields in Lightning App Creation
App Name – This name appears in the navigation bar so your users can see the name of the app they’re currently using.
Developer Name – Used by the API and managed packages, this name must be unique across all apps.
Description – Help your users by entering a brief description of your app. The description displays alongside your app icon in the App Launcher.
Image – App images represent your app in Lightning Experience and mobile. Choose a JPG, PNG, BMP, or GIF image that’s smaller than 5 MB. For best results, upload an image that’s 128 by 128 pixels. Images larger than the maximum display are resized.