Co-Sleeping is the practice of sleeping in close proximity to the parents, and is used in the context of infants/ young children. It refers to the idea of sleeping in the same room as parents.
Co-Sleeping and bed sharing are often confused with each other. Bed sharing is a form of co-sleeping wherein the infant/child shares the same bed as the parents.
For safety reasons the likes of American and Canadian associations of Pediatrics strongly recommend co-sleeping with your child, especially till 6 months of age. However the practice of bed sharing is discouraged as it is unsafe and unhygienic, and is also illegal in some countries world over.
Your baby is the safest sleeping next to you, on a cot secured from all sides on a firm and safe mattress.