Zakat is the third pillar of Islam. Allah has made it obligatory for the wealthy, as a rightful share of the poor and needy in their wealth. Zakat is given once a year. Its main purpose is—

• to return the rights of the poor.
  
• to eliminate poverty from society.
  
• to purify wealth.
  
• to establish justice between the rich and the poor.
  
• to keep people away from miserliness and arrogance.
  

Holy Quran Allah said:
“Give them their due right from your wealth.”
— — Surah Adh-Dhariyat, 51:19

Here it clearly shows:
➤ Zakat is not charity, but the rightful share (due) of the poor.