Antique furniture can be divided into the following categories. The prudent collector knows which their pieces fall into and thus the proper market for each. Over-paying or selling for less than an item is worth is always misunderstanding the market. A proper formal appraisal and market report, from a certified appraiser,alleviates this problem.
Second Hand - furniture from the 1920's through the 1950's that have some age and costly when new. Many old collectors mistake these as "antiques". An antique is something at least 100 years old.
Utilitarian - old furniture of little interest to museums but ideal to decorate with and use every day (dry sinks, joint stools, roll top desks etc. the list goes on).
Decorative - items of better quality then produced today and future collectable (Baker furniture, Louis XIV Revival etc.)
Museum - furniture too fragile to use, but placed in a collection to add ambiance or fill a gap in a complete collection (French, Louis XIV, Tudor, Medieval etc.)