http://www.cytometry.org/Resource-Center//

http://isac-net.org/Education/CYTO-U.aspx

Here are a couple of free resources from BioRad and BD, respectively:

https://www.bio-rad-antibodies.com/static/2017/flow/flow-cytometry-basics-guide.pdf

https://www.bu.edu/flow-cytometry/files/2010/10/BD-Flow-Cytom-Learning-Guide.pdf

Also, the book "Flow Cytometry Data Analysis: Basic Concepts and Statistics" by James V Watson is a good overview of the maths behind flow.

https://www.barnesandnoble.com/w/flow-cytometry-data-analysis-james-v-watson/1111442118?ean=9780521019705

Hi Alice, this is a question that comes up quite frequently and I would recommend the following articles as the best possible resources that I know:

Chapter Basic Multicolor Flow Cytometry

Article Guidelines for the use of flow cytometry and cell sorting in...

Furthermore, the online learning center of ThermoFisher has a set of pretty good articles and videos explaining basic concepts:

https://www.thermofisher.com/us/en/home/support/tutorials.html

Lastly, joining the International Society for Advancement of Cytometry (ISAC) or attending their annual congress will also provide a lot of learning material.

Have fun learning about flow!

Thank you all very much!