This thesis addresses the main research question: “How to help customers to communicate product properties accurately for a C2C secondhand clothing online platform?” Communicating product properties in C2C online marketplace is important because clothing is “high-touch” experience goods that need sensory evaluation to assess the product. The goal of the thesis is to provide design recommendations to improve engagement between sellers and buyers in C2C secondhand clothing online marketplaces by communicating secondhand product properties accurately.
 
To address the key research question, a comprehensive literature review was conducted, identifying a general research gap: there have been no specific studies on communicating product properties in C2C secondhand clothing online marketplaces. To bridge this gap, we conducted a Sequential Mixed Research method using qualitative research (in-depth interviews) for the first phase, with the key research question: “What are the key factors influencing customer satisfaction in selling and buying clothing in the online C2C platform?” These are the key findings from the in-depth interviews:
1. Customers often encounter measurement inaccuracies, as many of them struggle to determine how the clothing will fit without trying
2. There is often a lack of information about signs of use although customers expect some flaws in secondhand items, but often there's a lack of information about signs of use
3. Tactile experience is missing in online shopping, making it difficult to gauge the material of the secondhand clothing
4. Customers frequently feel disappointed when the actual color differs significantly from what they saw online.

In the second phase, we conducted quantitative research (online survey distributed across Europe), with the key research question: “What solutions are feasible to implement on the platform to enhance the engagement between seller and buyer in the C2C online platform?” We integrate the results of both phases of the research to answer the questions. These are the key findings from the online survey:
- Provide visual and textual information to cater to buyers' needs, which often hinders their experience when lacking in the platform
- Allow sellers to easily provide visual and textual information of their product in the product listing page without hassle (e.g feel encouraged to put detailed measurements, provide clear images, etc)

The insights revealed there is a necessity in providing detailed information about product properties such as detailed measurements, signs of wear, true color representation, and tactile descriptions. To address this need, a digital interactive prototype was developed that includes design features that enable sellers to offer accurate information about their items. The prototype was evaluated to measure its impact on seller and buyer engagement, which involved user testing to gather feedback on the usability of the prototype.

This study provides suggestions by examining solutions to encourage customers to effectively communicate product properties. On C2C platforms, individual sellers upload their own images and text for product information, resulting in varying levels of quality and clarity. The quality and clarity of these inputs are crucial for establishing trust, a driver of long-term success in C2C online platforms.

This research and design concept contributes to C2C secondhand online platforms by enhancing the communication of product properties. In C2C online platforms, sellers provide their own text and images for the product listings, which are reflected on the product detail page viewed by buyers. This information is crucial for buyers when making purchase decisions. We propose the following guidelines for sellers to improve product listings: 
1. Visual guidance to help users input detailed measurements 
2. Guidance for capturing and displaying the true color of products
3. Guidance for encouraging sellers to provide signs of wear 
4. Guidance for capturing the item’s dimension and tactile qualities through video