The four types of Shirk are:

Shirk is associating partner with Allah or giving a share (of those which belongs to Allah alone) to others i.e. ghairullah. Shirk is the most hated sin by Allah. Allah says in the Qur’an that Shirk is the greatest sin (Inna -al-shirka Zhulm al-azheem Quran 31:14). He also says that He will forgive all other sins if he wishes, except Shirk (Quran 4:49). So, it is our duty to be wary of the damage it can cause to our belief and avoid it.
The four types of Shirk are:

Shirke Ismi or Shirke Jali
Shirke Fi’li or Shirke Kafi
Shirke vasfi or Shirke Akhfa
Shirke Zaathi or Shirke Khafiyyul Akhfa

Shirke Ismi or Jali:

This is the most dreaded Shirk. It is associating Ghairullah (anything other than Allah) with Allah in worship; accepting Ghairullah as fit to be worshipped or worshipping Ghairullah. One has to be clear of this Shirk to become a Muslim. If a Muslim falls in this Shirk, all his previous good deeds will be wiped off (habthe a’mal). May Allah save us all from this.

Shirke fi’li or kafi:

This is a latif (delicate) shirk, which most of us do practice, unknowingly. This does not make one a Mushrik , who Allah censures in the Qur’an but, it does deprive the dharajaths (high positions in Allah’s sight) in the path of Sulook (way towards Allah).

This Shirk is believing or thinking that Ghairullah can give us profit or loss, victory or defeat, good or bad on their own; believing that a Ghairullah, be it a Prophet or a Vali (friend of Allah) can give us gain or loss or act without the power of Allah.

Allah says in the Qur’an, "la hawla wa la quwwatha illa billah" (there is no power other than the one with Allah). Yes, no one can act on their own, whatever their status, except with the power and help of Allah. It is Allah who is helping us to act; even the smallest movement of our fingers is due to Allah providing us His power. The Mu’jizas and Karamath’s (miracles) of the Prophet’s and Awliya are but the manifestation of Allah’s power through them. If anyone thought that they did it on their own, he falls in Shirke Fi’li. In truth, they perform it with the help of Allah. Praying for the sake of Jannath (heaven) or fearing Jahannam (hell) or Riya (acting to satisfy Ghairullah) also come under this category of Shirk.

Shirke Vasfi or Akhfa:

It is the Shirk that involves the Zaathi Sifath (own characteristics) of Allah. It is thinking or believing that the Ummuhathus Sifath (mother of all characteristics), Hayath, Ilm, Iradha, Khudhrath, sama’ath, basarath and kalam (explained in the article on kalima) that we find in the creatures are their own. They are in fact Allah’s and He has been merciful to manifest them on His creatures. At this point I would like to mention that Allah sees without eyes, hears without ears, speaks without mouth or sound; His action is without movement.

This Shirk will hinder the ascension of the salik to higher grades of Makame Kurb (status of nearness to Allah).

Shirke Zaathi or Khafiyul Akhfa:

Only the great saints and awliya have been saved from this Shirk. It is believing or accepting the very existence of Creatures of their own. They exist only due to the subsistence (ujoodh) of Allah. Creatures are but a form that don’t have anything and Allah supports them with his ujoodh. Shunning from this Shirk is of the very highest grade of Iman (belief) and those who are encompassed in this Shirk are denied the state of Shuhoodh or Ihsan