Factors affecting supply

•Prices of other factors of production.
An increase in the price of, say, hops, will increase the costs of a brewing firm and so for any given price the firm will not be able to brew as much beer. Hence, the firm's supply curve will shift to the left. The same would be true for changes in wage costs or fuel costs.
•Technology.
The supply curve drawn above assumes a 'constant' state of technology. But as we know, there can be improvements in technology that tend to reduce firms' unit costs. These reduced costs mean that more can be produced at a given price, so the supply curve would shift to the right.
•Indirect taxes and subsidies.
When the chancellor announces an increase in petrol tax (again!), it is the firm who actually pays the tax. Granted, we end up paying the tax indirectly when the price of petrol goes up, but the actual tax bill goes to the firm. This again, therefore, represents an increase in the cost to the firm and the supply curve will shift to the left. The opposite is true for subsidies as they are handouts by the government to firms. Now the firm can make more units of output at any given price, so the supply curve shifts to the right.
•Labour productivity.
This is defined as the output per worker (or per man-hour). If labour productivity rises, then output per worker rises. If you assume that the workers have not been given a pay rise then the firm's unit costs must have fallen. Again, this will lead to a shift to the right of the supply curve.
•Price expectations.
Just as consumers delay purchases if they think the price will fall in the future, firms will delay supply in they think prices will rise in the future. It's the same point but the other way round.
•Entry and exit of firms to and from an industry.
If new entrants are attracted into an industry, perhaps because of high profit levels (much more on this in the topic 'Market structure'), then the supply in that industry will rise at all price levels and the supply curve will shift to the right. If firms leave the industry then the supply curve will shift to the left.