With Power Apps citizen developers can build apps and portals without using traditional code. There are several different no-code/low-code approaches to create business logic to your apps, e.g. by using Power Automate flows or workflows. Professional developers can extend apps with code, e.g. by creating business logic using plug-ins or Azure functions. Power Apps Component Framework is the framework used by Microsoft to create components to model-driven apps. Professional Developers can use this framework and create their own custom components, PCF controls.
The former CRM functionality from Microsoft, Microsoft Dynamics CRM, has evolved into a number of model-driven apps built on the Power Platform. Partners and customers to Microsoft can extend these apps or create custom model-driven apps. Where to start? In order to build apps you go to Maker Portal, make sure to choose the intended environment and start making your apps!
Before it was launched Power Apps had the code name Kratos. On the 30th of November 2015 Microsoft PowerApps was introduced on the Official Microsoft Blog Introducing Microsoft PowerApps.
There is an article from Business Insider from that same day.
Public Preview was announced on the 29th of April 2016 Announcing Public Preview for PowerApps.
Microsoft PowerApps became General Available on the 1st of November 2016 Microsoft PowerApps and Flow are General Available starting tomorrow.
In 2019 PowerApps changed name to Power Apps. The "new name" aligned well with the newly rebranded Power Automate (former Microsoft Flow), Power BI and the new kid in town Power Virtual Agents.