MDIs, or Metered Dose Inhalers, are devices used to deliver medication directly to the lungs. They are commonly prescribed for conditions like asthma and chronic obstructive pulmonary disease (COPD). MDIs release a specific amount of medication in aerosol form, allowing patients to inhale it easily. Using an MDI typically involves shaking the device, attaching a spacer if needed, and pressing down on the canister while inhaling. This method ensures that the medication reaches the airways effectively. Proper technique is essential for maximizing the benefits of the medication and improving respiratory health.