An assisted living facility is a community for seniors who cannot live independently. One of the reasons that assisted living centers are appealing to many people is that they offer a relatively high level of independence.
A line segment is a piece, or part, of a line in geometry. A line segment is represented by end points on each end of the line segment. A line in geometry is represented by a line with arrows at each end.
A market segment is simply a subdivision or part of an overall market with specific and distinctive characteristics. As opposed to mass marketing where you direct your marketing activities to the entire market, in market segmentation, you tailor your marketing to the needs and wants of the particular market segment.