So what are web apps?
Simple put web apps are custom tailored website that can work and appear just like a native mobile app. The user can even bookmark the web app on their phone, so it will appear as any app would.
Web Apps are great when you don't need the advanced features of a full blown mobile app, but still want to offer clients or customer a great mobile experience.
Even today many sites are not mobile friendly. If someone visits your site with a mobile device and has a band experience, like things being too small or hard to navigate, odds are that they will not come back anytime soon.
With 30% of the people using mobile devices and tablets to serach the web can you afford to take that chance?