In many countries the term local derby, or simply just derby (pronounced 'dar-bee' after the English town) means a sporting fixture between two (generally local) rivals, particularly in Association Football. In North America, crosstown rivalry is a more common term.
Although there are no strict rules, derby games in France are commonly divided into three categories - derbies, local derbies and classicos (originally a Spanish expression).
A derby is a game involving two teams from neighbouring cities, a local derby would involve two teams from the same city and a classico involves two teams from two cities quite far apart geographically which have developed a great rivalry along the years - such as PSG and Marseille in football for example.
Local derbies
Local derbies are extremely rare in France, especially in football. There are two main reasons for this.
Before WW2 derbies were quite common but they disappeared when new national leagues were artificially created - by the Vichy regime - involving only one team from each region. This fateful decision caused many clubs to merge or temporarily disappear and even though some clubs were relaunched after the war the damage had already been done.
The other reason is purely financial. Because clubs in France rely heavily on public subsidies from local and regional councils, they have to share this money with other clubs from the same region or town. As a result of this, it is usually more economically sensible for two clubs from the same area to merge rather than to compete against each other in the same league.
The last derby in the French top-flight, was the Paris derby that took place during the Ligue 1 1989-90 season between Paris Saint-Germain and Racing Paris. Previously a short-held rivalry occurred in the 70s between Paris FC and PSG, owing to their merger and split in 1970. In the 1930s, there was a fierce rivalry between Ligue 1 founding members CA Paris, Racing Paris and Red Star. Originally both founded in Paris, Racing and Red Star have moved out to the suburbs since then. However, back in the 1990s Racing did share PSG's Parisian stadium during their brief spell in Ligue 1. US Créteil was founded in the southern suburbs of Paris in order to compete with the other areas of the city, and had remained in the same suburb throughout its history.
Prior to this, derby games outside Paris were more common, particularly in the 1930s. For example, Lille was the home of SC Fives and Olympique Lillois (both merged in 1944 and became Lille OSC). Another example was Roubaix, home of Excelsior and RC Roubaix who even met in the 1933 final of the Coupe de France, Excelsior being the winner (both merged with Tourcoing in 1945, RCR unmerged in 1963 and Excelsior in 1970). Between 1930 and 1960 there was a regular lower league local derby between FC Ajaccio and AC Ajaccio.
The only regularly occurring city derbies and which uphold their rivalries in recent years in France are the Parisian derbies between Red Star, US Créteil and Paris FC in the second and third tiers, and the Ajaccio derby between AC Ajaccio and GFCO Ajaccio.
Ajaccio - AC Ajaccio (L2) vs Gazélec Ajaccio (L3). Paris - Paris Saint-Germain (L1) vs Paris FC (L2) vs Racing Paris (N3) vs Red Star (N3) vs US Créteil (N)
Clubs from the same city but playing in different leagues can meet in the Coupe de France however, even if, this rarely happens.
Taking into account all the clubs playing at at least semi-professional level, the top four divisions; Ligue 1, Ligue 2, National, National 2 and National 3, additionally the following derbies could occur, although they do not evoke any emotion among fans:
Bastia - SC Bastia (N3) vs. CA Bastia (N2) vs. ÉF Bastia (N3) Bordeaux - Girondins Bordeaux (L1) vs. Stade Bordelais (N2). Lyon - Olympique Lyonnais (L1) vs. AS Lyon-Duchère (N). Marseille - Olympique de Marseille (L1) vs. Endoume Marseille (N3) vs. Consolat Marseille (N). Reims - Stade de Reims (L2) vs. Reims Sainte-Anne (R1). Strasbourg - RC Strasbourg (L1) vs. Vauban Strasbourg (R1). Toulouse - Toulouse FC (L1) vs. Toulouse Fontaines (R1).
Regional derbies
Whereas city derbies are quite rare in France, local regional derbies on the other hand are very common. And because French people usually identify primarily with their town or region (Esprit de clocher), these local derbies do attract much attention.