Shopping for second-hand clothes has gone from a niche fashion statement to trendy in just a matter of years, which is a huge win for the environment. In fact, the industry the resale of second-hand clothing is currently worth $24 billion and is expected to reach $51 billion in five years. Most exciting is that this exploding market is stealing revenue from fast fashion, an industry that is notoriously unsustainable. In fact, secondhand retailer thred UP suggests that the resale market will overtake fast fashion if it continues to grow at this rate.