As already mentioned, this is definitely possible. I think the other answers do not provide enough information or understand the question, so let me provide a little more.
Yes, you can create a mobile application in HTML, either from scratch, using PhoneGap as a platform, or using a mobile framework such as jQuery Mobile .
PhoneGap allows you to create real mobile applications using HTML5, CSS and JavaScript and use the PhoneGap API to use the functions available on smartphones, such as camera, motion sensor, GPS, storage, etc.
Using jQuery Mobile, you will create a mobile website that must be accessed using your phone’s browser, however you can incorporate this infrastructure into the PhoneGap platform. This allows you to create a more familiar HTML5 comprehension application.
I think the question you should ask is which language should I use? It does not matter if the application is used online or offline. The important thing is in which language or platform you want to write it. There are drawbacks to using HTML5 for writing mobile applications (speed, scalability, quality, approval, to name a few).
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