The Tamagotchi V5 / Famitama / Familitchi has introduced a new feature called "Bonding."  The Bonding Level is a percentage stat that indicates how close the members of the family are to each other.

This bonding level increases when you train your tamagotchis when they ask for training (usually happens at 10:00 AM, 12:00 NN, 2:00 PM, 4:00 PM or 6:00 PM), use certain items (like the Magokorotchi, disco ball, or Gotchi King DVD), or play golf putt/shoe match (not applicable when your pets are in the first generation as these games need parents).  Take note that the bonding level is shown in percentage and in steps of 10% so doing these activities will take several tries to "see" an increase in the stat page of your tamagotchi.

So how important is this bonding level and your experience with your Tamagotchi?  So far in my playtime with the V5s (The pink and the fuschia one are both in the fifth generation turning sixth), if you're serious enough to see everything in a V5, it is the way to get a pure family, evolve your teenager into a certain adult character or see all the animations when you press the right button with no item selected.

Procuring a Pure Family

In my third generation in my fuschia V5, I successfully mated my Violetchi with 100% bonding to a Sukatchi via the dating show producing the pure Violet Family (a Mamavioletchi and Papakizatchi as parents, a Violetchi as adult, a Kizatchi as the younger child, and a Hanatarezoutchi as a pet.

However, in the fourth generation, I again successfully mated my Violetchi to a Sukatchi via the dating show.  At that time, the Violetchi had only 80% bonding with her family at the time of marriage.  This produced a common blended family with Furikotchi, Violetchi, and Nemutchi as adults when they grew up.

Getting a Certain Character

The level of bonding combined with what type of training type they get determines what adult character you would get.  If you want to get let's say a Mametchi, then you must train your tamagotchi with the 1st option (Smart) often so that at least one of your toddler males turn into either a Mamekatchi, Bakutchi or Korokotchi at the teenager stage.  You then need to increase your bonding levels to 80% - 100% so that it turns into a Mametchi.

You get different characters if your bonding levels are from 0%-30%, 40%-70% and 80%-100% by the time they evolve into adults.  Mix and match levels of bonding with a certain type of training to see different characters.

Different Animations

This is probably the least important impact of a bonding level.  There are different animations that the tamagotchis do when you press the rightmost button when there are no icons selected.  At a low bonding level, the tamagotchis will act confused.  The next level will have them running off screen, running back and sliding down the screen.  The next one will have the eldest child going near the screen.  The last one will have all of them going near the screen or if you have a pure family, get a special animation associated with that type. 

If you do find another reason to raise the levels, then feel free to comment away.