Introduction to string field theory, including comprehensive index and exercises for learners. Contents: 1) Introduction. 2) General Light Cone. 3) General BRST. 4) General Gauge Theory. 5) Particle. 6) Classical Mechanics. 7) Light-Cone Quantum Mechanics. 8) BRST Quantum Mechanics. 9) Graphs. 10) Light-Cone Field Theory. 11) BRST Field Theory. 12) Gauge-Invariant Interactions.