Tutorials

@chappie my English is very bad, so I can not translate them.
Maybe, you can use Google Translator for this…

@pedro – thanks. Wish I could help. How many FRT tutorials are there? If only one, it looks very general and is probably covered here anyway.

@chappie, yes only one and general.
The FRT has no secret, what else can we say in a tutorial?

Arguably, thumbnails is a topic for WP rather than FRT but I, as a novice, would be grateful to read here why FRT is needed and which image files it targets.

To begin at the beginning: what is a thumbnail? Is it the preview image which is displayed in the Image Library and in the Image Editor and in the Page Editor/Add Media window? Or is it also the different sizes of the uploaded image which are automatically created by WP or by responsive themes?

And does FRT delete all sizes of image which haven’t yet been added to a page or post? If yes then it is doing much more than regenerating thumbnails. For example, if I upload an image today but won’t be placing it in a page until tomorrow, will FRT remove it if I run it today?

And does FRT do anything as soon as I activate it or does it wait until I instruct it to scan?

And are there any special considerations for Retina-capable themes or does FRT treat them just the same as non-retina themes?

I’m sorry – this is very basic but I’m trying to understand the scope of FRT.

To begin at the beginning: what is a thumbnail? Is it the preview image which is displayed in the Image Library and in the Image Editor and in the Page Editor/Add Media window? Or is it also the different sizes of the uploaded image which are automatically created by WP or by responsive themes?

Image = File uploaded
Thumbnail = Many images with many sizes, automatically created by WP on upload event

And does FRT delete all sizes of image which haven’t yet been added to a page or post?

No. All thumbnails are deleted and regenerated

And does FRT do anything as soon as I activate it or does it wait until I instruct it to scan?

FRT should be used only when you change the size of your thumbnail patterns (small, medium, large) or when you add or remove any statement add_image_size of your theme

And are there any special considerations for Retina-capable themes or does FRT treat them just the same as non-retina themes?

Treat them just the same as non-retina themes

I’m sorry – this is very basic but I’m trying to understand the scope of FRT.

You are welcome =)

* PS: Sorry for my english

Thank you @pedro. Your English is good — infinitely better than my coding.