Simpily put, BIM is a computer technology dedicated to the AEC industry to visualize architectural designs with 3D models and record building information with property parameters. BIM is like a virtual building established using a computer. Since the building information is complete and associated to each other, you can:
1. Modify designs easily;
2. Output design documents (2D/3D images, or reports) easily;
3. Analyze models with different software in order to comply with environmental requirements or make improvements.