Beher (poetry)

Beher (Arabic/Persian/Urdu: بحر) in Urdu poetry is the meter of a sher (couplet). Essentially, beher is a specific pattern, combining the arkaans (dummy meaningless words) of Urdu prosody that define the "length" of a sher. However, generally beher is categorized in three classes: Short, medium, long, depending upon the length of the sher of the ghazal.
For a ghazal, since all the shers in it should be of the same beher, determining the beher of one sher (or even one line of the sher) is enough to determine the beher of the entire ghazal. For example, in this ghazal of Ghalib, notice the length and meter of the ashaars is same throughout.

Another example is:

This poetry was written by a great poet "Shaheer Ralvi".

The ghazal above is written in a beher called: khafiif musaddas makhbuun mahzuuf maqtu (Meter G8). This is a ten syllable beher and by the standards of Urdu poetry, is a chotii (small) beher.

There exist many behers, but mainly there are 19 behers used in Urdu poetry. These behers are further distributed in parts, but they are not part of this topic. The names are:

1. Bah’r Hazaj Saalim

Ma - faa - ii - lun Ma - faa - ii - lun Ma - faa - ii - lun Ma - faa - ii - lun

Bha - rii duni- yaa sa - hii le - kin thi - kaa- naa ham bhii paa leN- ge

Ja - haaN do gaz za - miiN ho- gii wa - hiiN ham ghar ba - naa leN- ge

Classic by Allama ‘Iqbal’:

Mitaa de apnii hastii ko agar kuchh martabaa chaahe

ki daanaa Khaak meiN mil kar gul-e-gulzaar hotaa hai

...
Wikipedia