A court process to determine some of the important rights and relationships between the spouses, but does not divorce them. So, the spouses are still married, and many legal relationships do not change, like property and debt obligations or rights. The decree for legal separation can specify various relationships between the spouses like child custody, parent-child access (visitation), child support, and Spousal maintenance (alimony) as well as a division of community property and debt up to the date of the court order, but all the legal rights and relationships resulting from marriage are not ended as with divorce.
Source: Superior Court of Arizona, Maricopa County
You and your spouse or domestic partner can end your relationship but still remain legally married or partnered, and get court orders on parenting and money issues, with a judgment of legal separation.
Source: California Courts.