From WikiPilipinas: The Hip 'n Free Philippine Encyclopedia
With its nearest translation as "servant" or "slave," people belonging to this social class are not completely free, although they enjoyed some benefits to barangay land - they had rights to food, shelter and work. If situation calls for it, an alipin could lose his or her rank and rights, for instance, when he or she committed a heinous crime, but was not executed.
A person became an alipin when he or she was captured from the war, punished for a crime, unable to pay debts, bought as a slave or born illegitimately. The class also include those born and raise by parents of the alipin class, especially those who have parents who died with unpaid debts. Such are called gintubo.
 Alipin Subclasses
There are two types of alipin - the namamahay and the sagigilid (or saguiguilid).
- Aliping Namamahay, translated as "householder," refers to an alipin who enjoyed rights and privileges to land, had his or her own house that are usually within the domain or territory of his or her master. In a sense, people belonging in this subclass were actually free, however their status was not permanent. A person became a namamahay when he or she is demoted from a higher rank, or promoted from being a sagigilid. He or she paid tribute or buwis which depends on his or her arrangement from the master. When the master's children are to be married, the namamahay was obliged to offer gifts.
- Aliping Sagigilid, translated as "hearth slave", refers to those alipin not enjoying rights and privileges. Purchased slaves and those captured from wars belong to this subclass. A sagigilid was highly dependent with his or her master, since had to provide him or her with food and shelter. The master had control over the sagigilid that he can easily sell his slave to another master. When this slave married, the master need not to support his or her family, and he or she will rise to being a namamahay. A sagigilid could buy his freedom in gold - for 30 golds, he or she can be freed from his or her master; and for 90 pesos, he or she can be promoted to timawa class.
- Arcilla, Jose S. Kasaysayan Vol. II - The Spanish Conquest. Philippines: Asia Publishing Company Limited, 1998.