Why did bill clinton get impeached

Although proceedings were delayed due to the bombing of Iraq, on the passage of H. Res. 611, Clinton was impeached by the House of Representatives on December 19, 1998, on grounds of perjury to a grand jury (first article, 228–206) and obstruction of justice (third article, 221–212).
Charges: Perjury (2), obstruction of justice, abuse of power
Accused: Bill Clinton, President of the United States
Outcome: Acquitted by the U.S. Senate, remained in office