I’ve been asked several times about the difference between Quality Assurance Engineer (QA) and Tester (QC) and I figured out that even people who develop software confused such simple things, so, what about the others? But you know what, they don't care, and it is their right!
People just need quality products! Managers want bug  free software of higher quality, users want quality apps, and this can be achieved through testing  no matter what. But what does that mean? What is Quality? It is all about satisfaction, that's it! The measure of quality is the happiness of the end-users! How to reach that abstraction becomes a true test for team .
While developing any product, especially software without testing, we face risks  and this is likely related to funds loss . So, if you don't care about testing but you need quality think twice and let quality assurance processes get to work. This applies to all team members, but mostly to Engineers who master test design  - Quality Assurance Engineers.
So, the intention that man should be happy with quality apps is solved with best practice approach . Once you get involved in testing you will learn about types of testing  and test documentation like test plan. Then you can handle test cases  based on test design techniques . After all, you will discover automation and by then will know the difference between QA and QC .
Glossary, simple way:
mismatch between actual and expected behavior
complete product examination through verification, validation based on specs for issue detection https://smartbear.com/blog/test-and-monitor/verification-and-validation-the-difference/
people who develop applications like designers, programmers, testers
(a) the possibility of something bad happening (by Cambridge dictionary); (b) action in the hope of a good outcome (by google dictionary)
(a) 125 Million Mars Probe Lost Due to Simple Math Error http://articles.latimes.com/1999/oct/01/news/mn-17288 (b) The many human errors that brought down the Boeing 737 Max https://www.theverge.com/2019/5/2/18518176/boeing-737-max-crash-problems-human-error-mcas-faa
testing pyramid, a framework for designing a test suite that optimizes for speed of tests execution with confidence that your application works as expected https://www.codecademy.com/articles/tdd-testing-pyramid
locate Seven Testing Principles at International Software Testing Qualifications Board https://www.istqb.org/downloads/send/51-ctfl2018/208-ctfl-2018-syllabus.html
the different types of software testing by Atlassian https://www.atlassian.com/continuous-delivery/different-types-of-software-testing
steps to reproduce with expected results based on requirements on the application
find the answer here https://www.portnov.com/session-1-questions
- Testing Dot Com, or allowance for the abuse of bugs in Internet startups, by Savin R. 2007
- A Practical Guide to Continuous Delivery by Eberhard W. 2017
- Software Testing Automation Tips, by Alpaev G. 2017