What is itjihad?

Answer 1

It is unclear what this question is asking since there is nothing called "itjihad".

The question may be asking about "jihad", of which there are two forms. One is an internal struggle to be true and faithful to Islam amidst all of the struggles and difficulties that the world presents. The second is the command to rise militarily in defense of Islam when Muslims are under attack, especially from non-Muslims. This second form of jihad is popularly considered the "holy war" type of jihad.

The question may be asking about "ijtihad", which is process by which Islamic Scholars ('Ulemaa) and jurisprudents (Fuqaheh) use analogies and logical discussion to expand extent Islamic law to new situations.

To read more about Jihad or Ijtihad, please see the Related Question below.

Answer 2:

Most simply, Ijtihad is the process by which Muslim scholars adapt Islamic law (Sharia) to new situations. It is done using a process of analogies and similitudes.