Europe's gas markets are at widely varying stages of development; some markets, such as Germany and the UK, have sophisticated market structures reflecting their long histories as gas consumers. Conversely, some markets such as Spain and Portugal, are comparatively new consumers of gas and have immature infrastructures and markets. Significant differences also exist in terms of gas self sufficiency, the role gas plays in each country and in future demand growth rates. Despite these differences, all markets in Europe are united by the fact that gas demand over the short to medium term is certain to increase as economic growth, greater supply availability, environmental concerns and legislation and a concerted movement towards gas fired power generation all combine to drive demand. As this demand grows, and as indigenous supply becomes increasingly depleted, Europe will become more dependent on other sources of supply. North African and Russian gas will increasingly penetrate the European market, whilst gas from further afield, in the form of LNG, will also significantly gain market share.