As Salafiyyah is a connection to the Salaf.  The Salaf are companions of the Messenger of Allah (sallAllaahu ‘alahi wasallam) and those who follow them in good from the first three virtuous generations and then (all those) after them (who follow them and are upon their way).  This is Salafiyyah.  An affiliation to Salafiyyah means (that one) affiliates (his/herself) to that which the companions of the Messenger of Allah (sallAllaahu ‘alahi wasallam) were upon and the way of the people of Hadeeth.  The people of Hadeeth are those who are upon the Salafy methodology and follow it.  As Salafiyyah is the (proper) belief in the names and attributes of Allah, the (proper) belief in Qadar and the (proper) belief in the Sahaabah (companions of the Messenger of Allah (sallAllaahu ‘alahi was sallam) and so on and so forth.  

The Salaf believe in Allah and in His beautiful names and exalted attributes that He (Allah) has described Himself with; and that which He was described with, by His Messenger (sallAllaahu ‘alaihi wasallam).  They believed in (His names and attributes) in a manner that befits the majesty of Allah (Subhaanahu wat Ta’ala), without distorting them, nor resembling them to the creation, nor negating them nor explaining them with false and erroneous explanations.    

They believe in Qadar the good and bad of it and that a servant’s Imaan (faith) is not complete until he believes in the Qadar that Allah has decreed upon His Servants.  Allah says,

إِنَّا كُلَّ شَيْءٍ خَلَقْنَاهُ بِقَدَرٍ

“And verily We created everything with Qadar.”

[Suratul Qamar: 49]

As far as the (proper belief with regards to the) Sahaabah, this means the belief, that it is incumbent to be pleased with the companions of the Messenger of Allah (sallAllaahu ‘alahi wasallam) and that all of them are trustworthy and that they are the best of the Ummah and the best generation.  The belief that every one of them is trustworthy, opposes that which is believed by the Shi’ah and the Khawaarij who considered the companions of the Messenger of Allah (sallAllaahu ‘alahi wasallam) to be disbelievers and did not recognize their rights or the truth (of their noble position).  

Salafiyyah does not have a leader other than the Messenger of Allah (sallAllaahu ‘alahi wasallam).  The Messenger of Allah (sallAllaahu ‘alahi wasallam) is the Imaam of Salafiyyah and the example (that is to be followed).  The companions of the Messenger of Allah (sallAllaahu ‘alahi wasallam) are (also) examples (to be followed).  The foundation (or source) of this principle (can be found) in the statement of the Prophet (sallAllaahu ‘alahi wasallam),

“The Jews split into seventy one groups.  The Christians split into seventy two groups.  This Ummah will split into seventy three groups; all of them will be in the fire except  one.”  They (the Sahaabah) said, “Who are they (that saved group) O Messenger of Allah?”  He, (sallAllaahu ‘alahi wasallam) said, “They are the ones who are upon the like of what I and my companions are upon.” 

[Hadeeth collected by Imaam Abu Dawood, Imaam Ibn Maajah, Imaam Ahmad, and Imaam Ad Daaramee.  Graded hassan saheeh by Imaam Al Albaanee]

And his (sallAllaahu ‘alahi wasallam’s) statement in the hadeeth of Al ‘Irbaad bin Saariyah (radi Allahu ‘anhu) who described the Prophet’s (sallAllaahu ‘alahi wasallam) sermon, and that afterwards he (sallAllaahu ‘alahi wasallam) advised them to fear Allah.  He (sallAllaahu ‘alahi wasallam) said, 

“I advise you to fear Allah and to listen and obey (the Muslim ruler), even if a slave was to become your ruler.” 

Then he (sallAllaahu ‘alahi wasallam) ordered that his Sunnah and the Sunnah of the rightly guided khulafaa (plural of khaleefah) be followed.  He (sallAllaahu ‘alahi wasallam) said,

“Incumbent upon you is my sunnah and the sunnah of the rightly guided khulafaa after me, bite (hold) onto it with your molar teeth.  And beware of newly invented matters (in the religion), for verily every newly invented matter (in the religion) is a bid’ah and every bid’ah is a misguidance.”