As Salesforce indicates (https://developer.salesforce.com/page/Connected_Apps) a "Connected App" is an application that can connect to salesforce.com over Identity and Data APIs.
Connected Apps use the standard OAuth 2.0 protocol to authenticate, provide Single Sign-On, and acquire access tokens for use with Salesforce APIs. Connected Apps are designed to replace Remote Apps, which are now obsolete.
Connected Apps add additional levels of control, allowing administrators explicit control over who can use the application, and various security policies to be enforced by the application. Quality Clouds uses a Connected App to access the REST API and extract Org usage and profiling information for Operational Scans.
This page describes how to set up a Connected App on your Salesforce Org for use with Quality Clouds.
Look for Connected Apps in your development environment by going to Setup > Apps > App Manager and click on New Connected App (marked in red)
In Salesforce Classic, from Setup, enter Apps in the Quick Find box, then select Build > Create > Apps. Under Connected Apps, click New.
This will present a screen similar to that shown in the following figure:
Fill out only following fields and leave the rest blank:
Connected App Name
+44 20 3290 0456
QualityClouds connection for REST API calls
Check Enable OAuth Settings.
Set the Callback URL to https://login.salesforce.com/services/oauth2/callback.
In Available OAuth Scopes, select Access and manage your data (api).
Click Add. This setting allows Quality Clouds to access the logged-in user’s account using APIs, such as REST API and Bulk API.
Click Save and Continue
Click App Manager again. Locate your newly created QualityClouds and click the dropdown arrow on the far right.
Note the Consumer Key and the Consumer Secret values (click the Click to reveal button to see the secret key).