Computer security is a burning subject of the modern era due to sudden development of technology. Security systems are constantly under threats of cyber criminals whose actions can cause severe damage. Banks and financial institutions are putting security as their priority since it's not only their client’s money on stake, but also their identity. As the world and technology progress, virtual reality starts taking over- slowly, but surely. This paper will discuss the most important guidelines for computer security in general, but also focus on security in banking. The first part of this thesis is focused on the history of security in general, from beginning of human race till nowadays. The second part is focused on computer security, mostly referring to the learnings of Carl Landwehr, but also other authors. Since this subject is very technological, many Internet sources were used for definitions in progressed cyber space. Bank security systems were presented from two aspects- physical ways of securing and online security. Cyber future, hyper and virtual reality are discussed in the end of the thesis.