1 door leaf：The door leaf is the main body of the door, that is, the movable part for opening and closing. Its structure is usually layered and composite, just like a sandwich: Surface  layer: The outermost decorative surface, which determines the appearance of the door.

 Core material: The material sandwwetted in the middle, which determines the sound insulation, heat preservation and weight of the door.

 Honeycomb paper: Lightweight, environmentally friendly, and low-cost, it is often used for interior doors, but its sound insulation and sturdiness are slightly weaker.

 Frame: It is usually a keel made of solid wood or density board, used to fix the core material and install hinges and door locks.

2. Door frame：Also known as a door casing, it is a frame fixed to the door opening of the wall. It serves as the "support" and "partner" of the door leaf. The main components include the "vertical frames" on both sides and the "upper retaining frame" at the top.

 Sealing strip slot:  High-quality door frames are designed with dedicated slots for installing sealing strips, which are crucial for sound insulation, dust prevention, and heat preservation.

 Installation method: Usually, the levelness and verticality are adjusted by wooden wedges, then fixed to the wall with screws, and finally the gaps are filled with foam glue to enhance stability and sealing.

3. Hardware：The "joints" and "nerves" known as doors are of vital importance. Hinge: Connects the door leaf to the door frame and bears the entire weight of the door leaf. The quantity and intensity are directly related to the service life and safety of the door. A door is usually equipped with 2 to 3 hinges.

 Door lock: The core of security and privacy.

 Lock body: A mechanical structure installed on the side of the door leaf, responsible for controlling the entry and exit of the lock tongue (inclined tongue and square tongue).

 Lock core: The core that controls the operation of the lock body, and its security level (A/B/C grade) determines the difficulty of preventing technical opening. 

 Panel: The handles and decorative panels inside and outside the door. 

 Door stop: Installed at the bottom of the door leaf or on the ground/wall, it is used to fix the door after it is opened to prevent wind or accidental collision.

4. Sealing strip：This often overlooked component, however, is the "amplifier" of the door's performance.

 Material: Mostly elastic materials such as rubber, silicone or TPE.

 Function: Installed at the contact edge of the door leaf or door frame, when the door is closed, it is compressed, effectively blocking the transmission of air, sound and light. The sound insulation and heat preservation effect of a door is at least half attributed to the sealing strip.

       A door with excellent performance is the result of the precise coordination and collaborative work of the door leaf, door frame, hardware and sealing strip. Next time when you open or close the door, you can pay attention to these exquisite structures and feel the practical science they contain.