What does a "Cannot find symbol" or "Cannot resolve symbol" error mean?

What does a "Cannot find symbol" or "Cannot resolve symbol" error mean?

java compiler-errors cannot-find-symbol

java

Non-static variable cannot be referenced from a static context

java variables compiler-errors non-static

java

Error: Could not find or load main class in intelliJ IDE

java compiler-errors intellij-idea

java

How to view the list of compile errors in IntelliJ?

java intellij-idea compiler-errors

java

intellij idea - Error: java: invalid source release 1.9

java intellij-idea compiler-errors

java

Cannot make a static reference to the non-static method

java compiler-errors static-methods

java

Java JUnit: The method X is ambiguous for type Y

java testing junit compiler-errors package

java

"Code too large" compilation error in Java

java arrays compiler-errors code-size

java

How do I compile with -Xlint:unchecked?

java compiler-errors unchecked

java

Deserialize JSON with Jackson into Polymorphic Types - A Complete Example is giving me a compile error

java json compiler-errors polymorphism jackson

java

maven "cannot find symbol" message unhelpful

java maven compiler-errors settings

java

Why does this Java 8 lambda fail to compile?

java lambda compiler-errors java-8 void

java

Android gives error "Cannot fit requested classes in a single dex file"

java android compiler-errors dex

java

"Non-static method cannot be referenced from a static context" error

java compiler-errors static

java

How can Eclipse create a class with unresolved compilation problems?

java eclipse compiler-errors

java