Hash is a concentrate product composed of compressed or purified preparations of stalked resin glands, called trichomes, which come from the cannabis plant. Hashish may be solid or resinous depending on both preparation and room temperature; pressed hashish is usually solid, whereas water-purified hashish, often called "bubble melt hash", or simply "bubble hash" is often a paste-like substance with varying hardness and pliability; its color, most commonly light to dark brown, can vary from transparent to yellow, tan, black, or red. This all depends on the process and amount of leftover plant material (e.g. chlorophyll).
Please check the laws in your country of residence to check the legality of cannabis.