The metro is by far the most convenient way to get around Paris.  At no point within city limits can you ever be more than 400m away from a station.  There are 384 stops along sixteen different lines.  Additionally, there are five express lines called the RER (French abbreviation for Regional Express Network).  These trains run at regular intervals of 6 minutes and are considerably faster than the regular Metro.  To travel to any location outside the 20 arrondissements, you will need a separate ticket.  A single Metro ticket will cost €1.50, but packs of ten can be bought for €11.30.  One ticket is good for a single bus, RER, or Metro journey and allows for changeovers between the RER and the Metro.

Régie Autonome des Transports Parisiens (RATP)
Telephone: 0892 684 114/7714