Different types of economic planning can be seen in different models of socialism. Some systems use decentralized planning, where decisions are made collectively by many groups using detailed local information. Other systems use centralized planning, where experts at the top make decisions using overall or summarized information about the economy.
In an ideal socialist economy, engineers and technical experts would manage production based on real needs, such as how much goods are required, instead of using money or prices. These experts would be chosen or supervised in a democratic way. However, this ideal system was never fully achieved. For example, the economy of the Soviet Union continued to use financial methods like money and pricing for planning. Still, it also developed other ways to measure performance based on actual production, such as net material output instead of GDP.
Many models of socialist planning are mostly theoretical. They have not been fully applied in real economies because they require very large changes at a global level. In economics, when people talk about socialist planning, they often mean the Soviet-style system, also known as a command economy. There is still debate about whether this system was truly socialist, a form of state capitalism, or something else.
In some socialist models, planning completely replaces the market, so there is no need for money or price systems. In other models, planning and markets exist together, where planning guides the economy while markets continue to function in a limited role.