When do babies first start to speak proper words?

It has been observed that most babies say their first words between 12 and 14 months of age. And then again, there are many normal babies who do not speak until their 2nd birthday or slightly before or after that. While with other milestones such as sitting and walking, children take about the same time to develop (give and take a month or two), the same is not so with speech. Generally speaking it is during the 14 months to age 2 period when most babies begin to make attempts at speech. Speech growth is gradual during the early part but seems to escalate during the 20-24 months period. It is important to understand that progress in the ability to understand language varies from the progress to use language. In physically healthy babies the ability to understand language occurs around the 6-8 month period and this ability improves vastly over the two years. However in the case of spoken language it is not as easy to indicate the pace at which language is acquired and can vary by as much as a year in toddlers of the same age.