A tester is the only person in a software project who has priviledge of knowing the product end-to-end. This is unlike their developer counterparts, who are restricted to certain feature or module.
Testing is considered a natural trait in any person. I feel this is a misconception. Though, testing is a natural activity, but It needs more skills, passion and attitude. Tester's only get better by practice. The more complex the software the more challenging it is for any tester.
There may be few simple applications, which gives the tendency that testing is simple. For me, testing is an interesting & challenging activity, where I can use and apply my skills. Testing is not bounded to one specific area, unlike developers who are labeled by the technology. EG; Java developers, C++ developers. Even there are many agencies or companies who try to label testers as database testers, windows testers. This is irrelavant.
Testing is similar to solving puzzles where you have different categories of puzzles, similarly different applications in testing terms. The skills needed are same but strategies may differ.
A tester who is testing a banking application cannot use the same technique/methodologies when he is testing a massive multiplayer game. There is nothing as a "Banking applications" tester or a "Gaming" tester. A tester who can test banking application can test gaming application as well and vice versa. The only thing that changes is domain.
Because testing is considered a natural trait, we can draw inspiration from different fields of professions for ideas & skills. Tester's can wear different kinds of hats based on situations
Testers are like
Detectives - Investigation skills
Journalists - Question asking abilities
Scientists - Analysis, problem solving
Politicians - Diplomatic
Military - Team management & leadership skills
Testing is NOT
-a simple activity
-something everyone can do
-the only activity of finding bugs
-about finding mistakes