84 Copyright © 2017, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 6 DOI: 10.4018/978-1-5225-2469-4.ch006 ABSTRACT The development of smart phones and other smart devices has led to the development of mobile applica- tions, which are in use frequently by the users. It is also anticipated that the number of mobile applications will grow rapidly in the next years. This topic has, therefore, been researched highly in the past years. Mobile applications gather user data and that is why privacy and security in mobile applications is a very important research topic. In this chapter we give an overview of the current research on privacy and security issues of mobile applications. INTRODUCTION The aim of this Chapter is to present the current research topics in the field of privacy and security of mobile applications. Mobile technologies enable people to use mobile applications on their smart phones and smart devices constantly. The main operating systems used in the majority of mobile devices are Android with 70% market share and iOS with 23% market share (“Mobile/Tablet Operating System Market Share,” 2016). Both most popular operating systems offer an app market for users with various mobile applications. Android users can download their mobile applications on Google Play Store and iOS users on Apple’s App Store (Degirmenci, Guhr, & Breitner, 2013). The app markets are centralised systems that offer applications to users, which means that the users cannot download the applications from other websites like they can on desktop computers, unless they change their security settings on their mobile devices. The mobile device users have downloaded over 100 billion mobile applications from app markets in 2015 (Statista, 2016). Mobile applications are usually put on the app markets by the third-party developers and with different purposes of the applications. When an application is uploaded to the Google Play Store it is not checked and usually the application is then available for download Models of Privacy and Security Issues on Mobile Applications Lili Nemec Zlatolas University of Maribor, Slovenia Tatjana Welzer University of Maribor, Slovenia Marjan Heričko University of Maribor, Slovenia Marko Hölbl University of Maribor, Slovenia