Apart from the client and server programs, the distribution also comes bundled with a C API and JDBC drivers.
Use your package manager if possible.
Otherwise, download the source. The latest filename of the latest version is postgresql-7.4.2.tar.gz. Read the install instructions that came with it, they are very helpful. Since this contains the jdbc driver as well, make sure java is setup correctly when you configure.
export PATH=$PATH:/usr/local/java/apache-ant-1.5.4/bin export JAVA_HOME=/usr/local/java/jdk1.2.2/ export JAVACMD=/usr/local/java/jdk1.2.2/bin/java ./configure --with-perl --with-java make make install
Currently there is no native Windows port, but a port comes with the standard Cygwin distribution. The category is Database, and the package is postgresql.