Because addition would destroy aromaticity, benzene instead reacts by electrophilic aromatic substitution (EAS): the ring's π electrons attack an electrophile, forming a resonance-stabilized arenium ion (sigma complex), which then loses a proton to restore aromaticity. Substitution, not addition, preserves the aromatic system. The core EAS reactions to know:

Halogenation (Cl₂ or Br₂ with a Lewis acid catalyst like FeBr₃)
Nitration (HNO₃/H₂SO₄, installing –NO₂)
Sulfonation (SO₃/H₂SO₄, and notably reversible)
Friedel–Crafts alkylation and acylation (AlCl₃ catalyst, installing an alkyl or acyl group; acylation avoids the carbocation-rearrangement and polyalkylation problems that plague alkylation)

"Swap the H"