Learning resources

To facilitate selfstudy, the resources here are classified by target audience. However, if you get stuck, don't hesitate to request help in the APL Orchard chat room or ask a question on Stack Exchange.
For nonprogrammers
Some of the best resources for somebody new to APL and programming in general are:
 APL Wiki's simple examples
 The Learn tab on TryAPL
 The book Mastering Dyalog APL by Bernard Legrand
 Learning APL with APLX (also as PDF)
 The Zark APL Tutor
 APL a Day: Introduction, Functions, Arrays, Values, Arrays have Shape
 A Practical Introduction to APL 1 & 2 (3 & 4 is for experts)
 Découvrez le langage APL: parts 1, 2, 3 by Eric Schrafstetter (in French)
Follow one or a couple of these tutorials through and play around a bit. To learn APL the advice is similar to that for learning other languages: have a goal (something you want to accomplish) and try to do it. Along the way you are sure to come across the pitfalls and gotchas of the language, and with time you may come to understand what APL thinking means.
For nonAPL programmers
This is a list of tutorials and other resources of interest to someone who knows about programming or is familiar with another programming language, but wants to learn more about APL.
 APL Wiki's advanced examples
 APL Wiki's Books
 APL Wiki's Papers
 APL Cultivation (chat lessons)
 TryAPL online interpreter with lessons
 APL Workshop
 Learn X in Y minutes
 Let's Learn A Programming Language
 Mastering Dyalog APL and its companion GitHub repository
 Zark tutorial
 Trying APL
 Artificial Neural Networks
 FizzBuzz
For novice APLers
If you already have a fair grasp of APL's primitive functions and operators, you can sharpen your skills by challenging yourself with these:
 APLcart Quiz: Be challenged to write a function for a given task or to explain what a given function does. (Based on APLcart data.)
 2016 Year Game: Find APL expressions involving exactly the digits 2 0 1 6 in that order to equal the numbers 0 to 100.
 2017 Code Golf Challenge: Find the shortest possible APL expression that evaluates 1…52 without using any number or character literals.
 APLeusis: A game for honing your ability to "think in APL".
For old APLers
In the last decade, several implementations have extended APL:
 New primitive functions:
⊢
Same, Right;⊣
Same, Left;⌷
Materialise, Index;≡
Depth, Match;≢
Tally, Not Match;⍸
Where, Interval Index;⊆
Nest, Partition
 Lambdas (dfns): Intro; Details; Operators; The dfns workspace (collection of categorized utilities with extensive comments and notes)
 Tacit programming: Dyalog APL documentation: Intro; Details; short video; long video; APL Cultivation lesson
 Other features: Keywords; Objectoriented programming
For advanced APLers
Here is a list of "howto"s on various subjects:
APL development [edit]  

Interface  Session ∙ Typing glyphs (on Linux) ∙ Fonts ∙ Text editors 
Publications  Introductions ∙ Learning resources ∙ Simple examples ∙ Advanced examples ∙ Mnemonics ∙ Standards ∙ A Dictionary of APL ∙ Case studies ∙ Documentation suites ∙ Books ∙ Papers ∙ Videos ∙ Periodicals ∙ Terminology (Chinese, German) ∙ Neural networks ∙ Error trapping with Dyalog APL (in forms) 
Sharing code  Backwards compatibility ∙ APLcart ∙ APLTree ∙ APLCation ∙ Dfns workspace ∙ Tatin 
Implementation  Developers (APL2000, Dyalog, GNU APL community, IBM, IPSA, STSC) ∙ Resources ∙ Opensource ∙ Magic function ∙ Performance ∙ APL hardware 