Hot rolled steel refers to steel that has been processed by heating it to a high temperature (above 1,000°C or 1,832°F) and then rolling it into various shapes such as sheets, coils, or plates. 

Pickling is a process used to remove scale (rust and oxidation) from the surface of hot-rolled steel by immersing it in an acidic solution (usually hydrochloric acid). 

Cold rolling is the process of rolling steel at or near room temperature (after it's been initially hot-rolled). This makes the steel harder, more durable, and more precisely shaped. 

Galvanized steel is steel that has been coated with a layer of zinc through a process called galvanization. The most common method is hot-dip galvanizing, where the steel is immersed in molten zinc.

Electrogalvanizing is a process where a thin layer of zinc is applied to steel via electroplating. The steel is immersed in a solution of zinc salts, and an electric current is used to deposit zinc onto the surface. 

Stainless steel is a type of steel alloy that contains at least 10-12% chromium, which gives it its corrosion-resistant properties. Additional elements like nickel, molybdenum, and others are often included for specific performance features. 

Aluminum is a lightweight metal that is commonly alloyed with other elements to enhance its properties. It is often used in applications where weight is a concern, as it is significantly lighter than steel.

Shaped steel refers to steel products that are rolled or extruded into specific shapes, such as I-beams, H-beams, channels, angles, and plates. These shapes are used in structural applications due to their strength and load-bearing properties.