A will with a minor trust is a will that includes additional provisions governing the care of your assets and their distribution to your children. You are also able to name a guardian for your children.
Parents of minor children absolutely need a will with testamentary trust provisions. If your family does not get along, there could be a custody battle, and the guardian of the person chosen by the court may not have the same values and child-rearing philosophy that you have, while the guardian of the estate will not have the flexibility with finances a trustee would have. In addition, the guardian of the estate will incur legal fees and court costs by making an official accounting to the court every year of how the money is spent. Finally, your children will usually receive their share of the assets outright at the age of 18 (in some cases 21).
In a will with a testamentary trust, you nominate the guardian(s) and decide at what age your child will receive their share of the assets. Only in rare instances will the court override your decision, such as if your choice is a drug addict or otherwise unfit to care for a child. You also choose the age at which your children receive their share of the assets outright. Most parents choose an age between 25 and 35.
Note, too, that life insurance passes outside of your will, so if you have life insurance for the benefit of your children, make sure that your policies list the trust as a beneficiary and not your minor child outright!
The Wall Street Journal published an excellent article titled “Deciding if Your Kid is Trust-Worthy” regarding this issue. Jessica highly encourages you to read it.