Microsoft has offered a number of forms automation products over the years, and the most long running was InfoPath which was released as part of Office 2003. InfoPath is a powerful and flexible product that stores user data in XML while offering form features such as rules, data validation, scripting, and integration with SharePoint. The popularity of SharePoint resulted in many organizations standardizing on InfoPath for forms, especially internal forms which are hosted on an intranet such as employee reviews, leave and payment requests, and human resources forms.
Microsoft has discontinued InfoPath, with mainstream support ending July 13th, 2021, and extended support ending July 14th, 2026.
Microsoft has named Power Apps as the successor to InfoPath. Power Apps has much in common with InfoPath. Both products include integration with SharePoint. Both are geared toward the citizen developer and do not require advanced developer skills in order to accomplish many functions. Both may be used to implement form-based solutions on your intranet.
There is no automated migration path from InfoPath to Power Apps. You will have to start from scratch and create Power Apps using your InfoPath forms to represent requirements such as the form layout, validation and business rules which should be handled by the form.
Power Apps is based on Dynamics 365 and is available only as a cloud service, not for deployment as standalone apps on a PC or running on a network server. This is different from InfoPath which could be run on premises or even standalone.
Power Apps does not seem to be designed with a goal of emulating paper forms or producing pixel-perfect renditions of standard forms such as government tax or employment forms. Instead, Power Apps is a modern web app, with excellent support for connected mobile devices.
Customers who are interested in a more paper-based approach which is closer to InfoPath may consider third party products such as Nintext Forms or creating SharePoint forms without InfoPath using custom .NET pages, Excel, or Word.