Write an article based on this "Allow each cat to see each other without physical contact. Let the cats meet face-to-face. Watch for signs of stress."
You’ve finally reached the step where the two cats see each other in the flesh! This is an exciting turning point, however, this initial introduction must be done slowly and carefully.  Introduce the cats together by placing a barrier between the two of them so there is no way they can come in full body contact.  You can place the cat inside a crate and place the crate in the same room as your existing crate. Another option is to stack two 36” high tension gates in the doorway that separates two rooms and placing each cat in their own room. A third option is to jam the door separating both rooms with two rubber door stops. Crack the door two to three inches, and make sure that neither cats’ head can fit through the opening. This method will allow for greater physical contact. Be sure that you are home to monitor the two cats’ interaction regardless of which barrier method you choose.  Do not let the cats interact until they both appear fairly calm around each other. Mild aggressive behavior, such as hissing and then walking away, can be normal behavior for cats who have been apart for several weeks.  Aggression is one way that cats communicate with one another, and mild aggression is usually okay as long as they are not fighting. It is now time to remove all physical barriers and allow the cats to have their first face-to-face meeting. Remove the new cat from her cage, or remove the gate or door barrier that was used to separate them.  Stand close by as the two cats come towards each other.  Be aware that the existing cat may stalk and chase the new cat, or the newcomer may do the same if the existing comes and enters the isolation room. Don’t worry; this is normal.  Just be sure to supervise both cats throughout the interaction.  Avoid holding either cat in your arms during this introduction . You could end up scratched or bitten if one or both of them becomes aggressive towards each other.If your cats do get into a fight, do not try to reach in and break it up with your bare hands.  Instead, grab a nearby squirt bottle, water gun, water hose, or water bottle. Then proceed to dose the cats with water; this will probably end the fight within a few seconds.  Remember that this process may take quite some time.  It could just a few days if you’re introducing two kittens to each other and potentially several months when introducing two adult cats. Cats can become stressed during the introductory period.  Make sure you pay attention for behavior that could indicate that either cat is street.  Stress signs include whimpering, hiding, vomiting, excessive grooming/eating/drinking, spraying, and urinating/defecating in inappropriate places.