The purpose and aim of Zakat-ul-Fitr is to enable those less fortunate than ourselves to celebrate the day of Eid-ul-Fitr and mark the breaking of the fast.
Zakat forms an obligatory act for all Muslims. Those who are unable to fast are required to pay in the form of Fidyah or Kaffarah. This also signifies a token of appreciation to Allah (SWT) for being granted the privilege of being able to observe this auspicious and beneficial month.
However, the amount of Zakat-ul-Fitr is universal amongst Muslims, regardless of individual income. It is based on the consumption particulars* of members of the household, to which there is a cash equivalent. This money is then given to those in need (the poor and needy, debtors, travellers and so on) before commencing Eid-ul-Fitr Salah (Eid-ul-Fitr prayer).
There are many terms for Zakat-ul-Fitr, such as Fitrana and Sadaqatul Fitr; which are all the same form of Zakat.
*For more details, please consult your local mosque.