There are four main types of noncovalent bonds in biological systems which help biomolecules to maintain their stability: hydrogen bonds, ionic bonds, van der Waals interactions, and hydrophobic bonds.
A hydrogen bond is an interaction between two atoms: one of the atoms is hydrogen (H), while the other may be any electronegative atom, such as oxygen (O), chlorine (Cl), or fluorine (F). Hydrogen bonds play the key role in protein folding, which helps the molecule maintain its stability. In DNA hydrogen bonds form complementary connections between base pairs.
Ionic bond is formed when a positively charged ion interacts with a negatively charged ion, during this process one atom transfers electrons to another (from donor to acceptor). Ionic bonds have contribution to the formation of three-dimensional structure of proteins. In DNA cationic proteins along with positively charged aminoacid residues (arginine and lysine) attract negatively charged groups in the DNA and stabilize it.
Van der Waals interactions are weak and nonspecific, they are created between two atoms that are very close to each other. They play an essential role forming three-dimensional structure of proteins that is necessary for their proper function and structure stability. Van der Waals forces stabilize the structure of the DNA helix.
Hydrophobic bond is an interaction between nonpolar molecules, such as hydrocarbons, in an aqueous environment in order to separate from water. The hydrophobic effect is a driving force for the folding of globular proteins. Together with Van der Waals forces hydrophobic bonds create stacking interactions which stabilize the overall structure of the DNA helix.