What is Section 377 in The Indian Penal Code

377. Unnatural offences.—Whoever voluntarily has carnal inter­course against the order of nature with any man, woman or animal, shall be punished with 1[imprisonment for life], or with impris­onment of either description for a term which may extend to ten years, and shall also be liable to fine. Explanation.—Penetration is sufficient to constitute the carnal intercourse necessary to the offence described in this section.