Vernacular architecture refers to buildings designed based on local needs, materials, and traditions rather than global or fashionable trends.

It's crucial for several reasons. Firstly, it's sustainable, using local materials and designs well-suited to the local climate, reducing the need for artificial heating or cooling. Secondly, it preserves cultural heritage, reflecting and maintaining traditional building techniques and styles. This can foster a sense of community identity and continuity. Additionally, vernacular buildings often have lessons to offer contemporary architecture in terms of sustainable and community-focused design. 

Understanding and preserving this type of architecture is vital in a globalized world where these local traditions are at risk of being lost.