Spark plugs are vital components of internal combustion engines, responsible for igniting the air-fuel mixture during the combustion cycle. A faulty spark plug can cause misfires, poor acceleration, and reduced fuel efficiency. Spark plugs vary by size and material depending on the vehicle type and engine requirements. The main types include copper, platinum, and iridium. Copper plugs offer high conductivity but wear out quickly. Platinum plugs last longer and perform steadily, while iridium plugs provide the best durability and efficiency but are more expensive. Choosing the right spark plug depends on your engine type, performance needs, and budget.