Thermal expansion is the tendency of matter to change its volume, area, or length in response to a change in temperature. As materials are heated, their molecules vibrate more and move apart, causing expansion; cooling causes contraction. 

Key Aspects of Thermal Expansion

Types of Expansion:

• Linear Expansion :Change in length,  (for solids).
• Area Expansion :Change in surface area,
• Volume Expansion : Change in volume, (for liquids/gases).

• Structures: Bridges and railways require expansion joints to prevent buckling.
• Materials: Mismatched expansion rates can cause materials to fracture.
• Environment: Ocean thermal expansion contributes significantly to sea-level in tide.