This seems simple maths behind, But I always get confused with the terminology of **"Fold change", "Log Fold Change" *(LFC)*, and  "Percentage of Change"**., When I see some of the figure descriptions given in **volcano plots**, specially X axis, I get confused. 

i.e. [Page 64][1] 

<a href="https://ibb.co/LtmQF2Q"><img src="https://i.ibb.co/zRp8M08/Capture.jpg" alt="Capture" border="0"></a>


When I google, I found [this figure][2] is easy to understand, but the figure description does not make sense for me. 
<a href="https://ibb.co/gFcsTDw"><img src="https://i.ibb.co/vvM2PJm/volcano-plot-chart-static.png" alt="volcano-plot-chart-static" border="0"></a>

for e.g.
If we take two-fold change;
isn't this the way we calculate LFC;

    LFC = Log2 (Foldchange) = Log2(2) =>1

if X axix is in Log2 fold change, shouldn't two-fold change denotes at **± 1**? Why they denote 2 fold change cutoff line in **± 2**?

-----------------
**Below VP; Fold Change greater than 2 times and significant P value less than 0.05**

See this example:

![enter image description here][3]


and this:

![enter image description here][4]

Could someone help me to understand this terminology ( **"Fold change", "Log Fold Change" *(LFC)*, and  "Percentage of Change"**. ) easily with an example? 


  [1]: http://www.nathalievialaneix.eu/doc/pdf/tutorial-rnaseq.pdf
  [2]: https://documentation.partek.com/display/FLOWDOC/Volcano+Plot
  [3]: https://cdn.xlstat.com/uploads/assets/Tutorials/DifferentialExpression/differentialExpression06.png
  [4]: http://chenyuan.date/images/Volcano-plot-unnamed-chunk-4-1.png

Hey @ Wuschel

These answers here helped me a lot in the beginning to understand these terminologies that I even saved in my browser bookmarks.

[Question: Difference between FC and LogFC][1]

[Dumb question about LogFC][2]

[Question: Report and compare log2FC vs FC][3]


I think it can help you about log2FC and FC, but about "% of change" I never read anything about it.

Another thing, if you want to learn how to create beautiful volcano plots read this tutorial "[Tool: EnhancedVolcano: Publication-ready volcano plots with enhanced colouring and labeling][4]"


  [1]: https://www.biostars.org/p/312980/
  [2]: https://www.reddit.com/r/labrats/comments/7odtki/dumb_question_about_logfc/
  [3]: https://support.bioconductor.org/p/66163/
  [4]: https://www.biostars.org/p/335751/