How twitter calculate trend?

[Suraj]

Twitter brings top ten trends on Home page. But how they calculate that? Is it on daily basis or weekly basis? If one hash tag is created one month before and till today it has 15000 twits but on specific day it got less twits (example 1000) and another hash tag created today and it has 2500 twits on that day.
So which trend come first?

[Alankrit]

actually they use javascript ..
For each '#' tag ...
the website automatically declares a variable ...
the count of which is equal to 0...
for every next time same, '#' tag is found ... it increments to one...
for example for each same '#' tag...
variable=variable+1;
initially
variable was 0;

[Karen]

Hope following url will help you:

http://www.npr.org/2011/12/07/143013503/...its-topics