Symbol API

com.intellij.model.Symbol (community/platform/core-api/src/com/intellij/model/Symbol.java) is the platform's generic replacement for "resolve a PsiReference to a PsiElement". A Symbol represents a semantic element in some model — a language, a framework, a database schema — and decouples navigation/find-usages/rename/documentation from PSI. A Symbol is not required to be backed by a PsiElement, and it is incorrect to try to obtain one from a Symbol.

Canonical examples from the docs: a Java local variable (backed by PsiVariable), a compiled class from JDK stubs (not tied to any project), a Spring bean (created dynamically by framework support, project-bound but not PSI-backed), a database column (defined by a data source, not PSI-backed and not project-bound).