Geosynthetic clay liners, bentonite liners, clay liners, and compacted clay liners are all specialized materials used in environmental engineering and construction to create effective barriers against fluid migration and protect natural resources. Geosynthetic clay liners (GCLs) are made by embedding a layer of bentonite, a clay with strong swelling properties, between geotextiles or geomembranes. When hydrated, the bentonite swells, forming a highly impermeable seal that prevents water and contaminant flow, making GCLs ideal for projects like landfills, ponds, and wastewater containment where a reliable, flexible liner is essential. Bentonite liners harness the unique properties of bentonite clay, which naturally expands to create an effective seal when exposed to water, making them a versatile choice in situations where self-sealing capabilities are beneficial, such as in hazardous waste containment or secondary containment systems. Clay liners, in general, provide natural, low-permeability solutions and are often used in projects that benefit from local sourcing of clay materials. Compacted clay liners (CCLs) involve tightly compacting clay in layers to achieve low permeability, often chosen for sites where locally available clay can be utilized to create a durable, thick liner. bentonite liner CCLs are typically applied where a natural barrier is preferred, though they require meticulous compaction to avoid cracking and ensure uniformity. Selecting the right liner type depends on factors like site conditions, environmental regulations, installation speed, and budget. Geosynthetic clay liners, with their lightweight design and consistency, simplify installation and offer reliable performance across varied environmental conditions. Bentonite liners and compacted clay liners each offer unique advantages: bentonite liners provide automatic self-sealing, while compacted clay liners can serve as natural, durable barriers when large quantities of compactable clay are available on-site. These liners are widely used for landfill covers, reservoir linings, mining projects, and various containment applications where environmental integrity and protection from contamination are paramount. Each liner type brings specific benefits suited to different applications, ultimately supporting sustainable engineering and resource protection across multiple sectors.