As in any partnership, business or personal, there are both assets and liabilities -- what you own and what you owe. First, we'll look at Assets -- What You Own.
"In most cases, unless there is a written agreement to the contrary, money earned by either you or your spouse during the marriage, assets purchased by either of you, and debts incurred by either of you are considered to be "marital assets and liabilities ." These "marital assets and liabilities" will be true even if an asset is bought in one name alone with the money earned by that person. Title to property alone does not determine distribution.
Any asset owned by a person before he or she gets married that he or she keeps separately titled (e.g., a home) will generally be distributed to that person upon divorce. Such an asset is called non-marital property. However, if that asset has increased in value due to the expenditure of marital funds, or funds of non-owner spouse during the marriage, or if that asset has increased in value due to the work efforts of either partner (even if it is only the work of the one that owned it before), then the increased value may be considered a marital asset that can be distributed to both husband and wife upon divorce.
If either spouse changes into joint names the title to an asset that he or she owned before marriage; or, if the person mixes the asset with marital assets (for example, if the spouse puts his or her house into both names or puts the money that he or she earns into a stock account he or she had before the marriage) then the whole asset may be considered to be a marital asset and may be distributed to both husband and wife upon divorce.
Gifts given by one spouse to the other are marital assets and can and will generally be divided should you divorce. Gifts given by outside persons to one party or the other individually, and not thereafter mixed with marital assets, are not marital property and will generally be awarded to the recipient of the gift upon divorce.
Now let's look at the Liabilities of Marriage -- What You Owe.