https://en.wikipedia.org/wiki/Software_bug

Most bugs arise from mistakes and errors made in either a program's design or its source code, or in components and operating systems used by such programs. A few are caused by compilers producing incorrect code. A program that contains many bugs, and/or bugs that seriously interfere with its functionality, is said to be buggy (defective). Bugs can trigger errors that may have ripple effects. Bugs may have subtle effects or cause the program to crash or freeze the computer. Other bugs qualify as security bugs and might, for example, enable a malicious user to bypass access controls in order to obtain unauthorized privileges.

Some software bugs have been linked to disasters. Bugs in code that controlled the Therac-25 radiation therapy machine were directly responsible for patient deaths in the 1980s. In 1996, the European Space Agency's US$1 billion prototype Ariane 5 rocket had to be destroyed less than a minute after launch due to a bug in the on-board guidance computer program. In June 1994, a Royal Air Force Chinook helicopter crashed into the Mull of Kintyre, killing 29. This was initially dismissed as pilot error, but an investigation by Computer Weekly convinced a House of Lords inquiry that it may have been caused by a software bug in the aircraft's engine-control computer.

This is very interesting topic in that we can appreciate the signicance of our code and how impactful errors can be. The fact that bugs can cause disasters of enormous proportions is a bit of a lesson to us all on being more and more aware when coding.

Adding this part in because I made the changes on the main branch accidently and so now I am making the changes on a new branch

Bugs are certainly large, tedious issues that developers face. Just in my personal experience, I have worked with bugs where sometimes when you address a single issue, others erupt and then you are trapped in a never ending loop of bugs. Luckily, no bugs I have worked caused massive real-world consequences such as the Therac-25 radiation therapy, but the occasional bug that comes up really should be accounted for in code reviews to ensure the end-user doesn't get affected. I also think an important point is where the article says that "It is common practice to release software with known, low-priority bugs," because it does show that even though we may really aim for perfection, it rarely (if ever) is achieved.

Bugs usually appear when the programmer makes a logic error. Various innovations in programming style and defensive programming are designed to make these bugs less likely, or easier to spot. Some typos, especially of symbols or logical/mathematical operators, allow the program to operate incorrectly, while others such as a missing symbol or misspelled name may prevent the program from operating. Compiled languages can reveal some typos when the source code is compiled.