Attention

TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.

You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.

For Developers

Extbase / Fluid

For learning extension development with Extbase and Fluid you can use one of these resources:

Understanding TYPO3

References

For a list of references look at References.

StackOverflow

You may also find some recommendations on this StackOverflow question.

Do look at the date of the answer, though. Some of the recommended resources are outdated.