Secondary bonds are weaker interactions compared to primary bonds (covalent, ionic, and metallic).
These include Van der Waals forces, dipole-dipole interactions, and hydrogen bonding.
Van der Waals bonds arise due to induced dipole interactions between neutral atoms or molecules and are responsible for holding together molecules in many soft materials.
Unlike covalent, ionic, or metallic bonds, which involve electron sharing or transfer, secondary bonds are purely physical interactions and are much weaker.