Coronavirus testing becomes an essential part of our lives, unfortunately. There are several types available, and it is important to understand differences among them. Here are three useful sources that can give you a good understanding.
The first one in an article by CNN that describes three main types of tests: PCR tests, antibody tests and antigen tests:
https://edition.cnn.com/2020/04/28/us/coronavirus-testing-pcr-antigen-antibody/index.html
The second one is on the types of tests available in the UK:
https://www.bbc.co.uk/newsround/52131937
And the third gives you a handy overview and a comparison table of available tests in Russia. It is in Russian only, unfortunately: