WML Cards and decks

The mark-up language defined by the WAP protocol is WML. At first glance,
WML looks like HTML and other mark-up languages. WML is designed with the
constraints of small narrowband devices in mind. These constraints include:

(a) Small display and limited user input facilities;

(b) Narrowband network connection;

(c) Limited memory and computational resources.

The most important difference between WML and HTML is that a WML page is
organized as a deck of cards, where each card represents one small
screen-full of information. Each deck consists of one or more cards. Each
deck begins and ends with the <wml> tag, and each card begins and ends with
the <card> tag. The entire deck is downloaded to the user's device when the
request is received and the user can then navigate between the various cards
using the card ID, without accessing the server (unless, the user requests
another deck). This reduces the number of trips between server and client
and allows some processing to take place within the client device.

Each card in a deck must be uniquely named.