Sometimes when people talk about marriage and divorce, the term separation becomes loosely used. People use the terms trial separation, permanent separation and legal separation without fully understanding that each describes a different segment in the trajectory from marriage to divorce. For example, a person may say, "My husband and I are legally separated," when she really means that they are living apart and have filed for divorce. Or someone else may say, "My wife and I are living apart," when in fact they have given up all hope of reconciliation and have decided that as of a particular date, they have separated with firm plans to end the marriage.

A permanent separation is sometimes placed above of a trial separation and below a legal separation. Each degree of separation, however, brings different legal parameters into play, and these may vary from one jurisdiction to another.

The act of separating, which is accompanied by announcements to family and friends that a divorce is in the offing, places a couple in a penumbra: the de facto end of a marriage that still exists de jure.

These issues and problems include, but are not limited to, assets acquired and the weight given them in property distribution; dramatic increases or decreases in assets; indebtedness incurred by one spouse during the separation; one-sided childcare and homemaker efforts of one parent; the occupancy of the marital home, including amortization of a mortgage.

In this, the phrase "during the marriage" comes into play because courts need a concept of the duration of the marriage for purposes of property division, particularly a date after which property is no longer subject to distribution. This date varies by jurisdiction. Some use the DOD, which is the date of divorce; some use the DOS, which is the date of separation.