There are four metro lines in Amsterdam, which are numbered 50, 51, 53 and 54. The latter three of these run from Central Station, while the 50 connects the Amsterdam Zuidoost to Amsterdam West and does not pass through (or stop at) Central Station. Lines 51, 53 and 54 all connect the city centre to the southest, running to Duivendrecht, Diemen and Amsterdam Zuidoost. In addition, line 51 also runs South, connecting the city centre to the suburb, Amstelveen. The four metro lines share only the first 5 stops, which are in fact underground, and then each line takes its own open-air way into the suburbs. Therefore, you will probably become familiar with the few actual underground stops of Amsterdam: Central Station – Nieuwmarkt – Waterlooplein – Weesperplein – Wibaustraat.
Metros in Amsterdam run quite regularly, about every ten minutes, operating (approximately) between the hours of 6am and 1am. In all stations where you can take metros, you can find maps of these networks, which are easily decipherable. Additionally, on the GVB website (below), there is a map that you can view and download that clearly details the four metro lines, both in colour and description, so it is easy to find your way via metro.
Since August 2009, the OV-Chipkaart (a pre-pay smart card that can be purchased and re-charged at the station and at local newshops and convenience stores) is the only accepted form of “ticketing” on the metros in Amsterdam, replacing the strippenkaart that is still widely used for other forms of public transportation throughout the city. A pre-paid ticket will amount to 2.80 euros from your smart card. If you have purchased a personalised OV-chip card, your travels are charged per/kilometer travelled, and you pay 0.145 euros/km with a base fee of 86 cents for your journey. On the GVB website, you can find a list of the specific products and fares that are offered for travel in and around Amsterdam, in relation to the OV-card.