Logic online (Courses, introduction-like papers, tutorials, online books etc.)
Basics

  1. First course in logic :

  2. Second course in logic :

  3. Theory of truth :

  4. Modal logic:

  5. Logique des conditionnels :

  6. Proof theory and substructural logics :

  7. Consequence relations :

  8. Arithmetic and metamathematics:

  9. Many-valued logic:

  10. Linguistics and formal semantics :

  11. Grammars :
Advanced

  1. Model theory, set theory, calculability :

  2. Proof-theory :

  3. Lambda-calculus :

  4. Arithmetics:

  5. Modal logics :

  6. Reflection principles:

  7. Infinitary logic and admissible sets :

  8. Algebra :