In the United States, many people are deciding to rent instead of owning a home.As a result, young people face one of the most competitive rental markets in the past 10 years.People under the age of 24, known as Generation Z, are competing with older generations.Many millennials, people aged 24 to 40, and baby boomers, those over 57, are looking for apartments too.People are choosing to rent for different reasons.One expert talked with VOA and said a lack of available houses is one big reason.Doug Ressler is with Yardi-Matrix, a research company that deals with business properties.He said that aging millennials who are starting families should be moving from rentals to home ownership.But in many cases, they are not because of the lack of available houses.And so, he said, these older millennials continue to rent.It is not just millennials or Generation Z, Ressler added.The number of baby boomers moving into rental properties has been growing in the last five years.