Which property qualifies for a 1031 exchange?

Could you please clarify for me what specific property qualifies for a 1031 exchange? I understand that it's a way to defer capital gains taxes on the sale of investment properties, but I'm unsure about the exact criteria that a property needs to meet in order to be eligible. Are there any restrictions on the type of property, such as commercial versus residential, or are there specific conditions that the property must be in? I'm interested in learning more about this process and how it can potentially benefit my investment portfolio.