Is it required to specify the length of the rental period, and what is the ruling on paying per click for advertisements?

There is nothing wrong with renting a space on a website for advertisements for other sites, so long as those sites do not contain anything haraam, such as websites for men and women to get to know one another, or websites for haraam music and movies and plays, or immoral audio and video links, or sites for followers of innovation, and so on. It is not permissible to advertise for these, because that is taking part with them in the haraam things that they are promoting. 

Allaah says (interpretation of the meaning): 

“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”

[al-Maa’idah 5:2]

It was narrated from Abu Hurayrah (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Whoever calls others to guidance will have a reward like that of those who follow it, without that detracting from their reward in the slightest. And whoever calls others to misguidance will have a burden of sin like that of those who follow it, without it detracting from their burden in the slightest.” Narrated by Muslim (2674).

 Seeking reward from Allaah for refraining from that which is haraam, dubious or confused is something that points to strength and certainty of faith, which bring glad tidings of a halaal provision, blessing and great reward. 

Secondly: 

As for the length of the rental period, one of the conditions of a rental contract being valid is that the period should be known, and the rent should be known. 

Ibn Qudaamah (may Allaah have mercy on him) said:  

There is no difference of opinion among scholars concerning the fact that it is permissible to rent property. Ibn al-Mundhir said: All of the scholars from whom we acquired knowledge were unanimously agreed that renting houses and animals is permissible.  

But it is not permissible to rent it except for a specified and known period. 

Al-Mughni (5/260). 

And he (may Allaah have mercy on him) said: 

If renting is done for some amount of time, it must be known, such as a month or a year. There is no difference of opinion concerning this as far as we know. 

Al-Mughni (5/251).  

It is permissible, in a rental contract, to agree on a certain amount of money every day, for example, or a certain amount of money every month, without stipulating the end of the period. Ibn Qudaamah (may Allaah have mercy on him) said in al-Mughni: If a person rents a horse for the period of a campaign for one dirham every day, what is narrated from Imam Ahmad is that (this contract) is valid, because ‘Ali (may Allaah be pleased with him) hired himself out every day at a rate of one date for every bucket, and the Ansaari did likewise, and the Prophet (peace and blessings of Allaah be upon him) did not denounce that. End quote. 

Based on this, you may either stipulate in the contract a complete period of time such as a month or a year for example, or you may stipulate the rent for each day, for example, even if you do not stipulate when the rental period will end. 

Thirdly: 

With regard to renting according to the number of clicks on the ad, it seems that there is nothing wrong with it, so long as there is agreement on the price per click, provided that you do not use a program to increase the number of people entering the site or hire someone to enter the site repeatedly.  

This is akin to what was narrated about the Sahaabah, that they worked to bring water, and were paid one date for each bucket. 

It was narrated that Ka’b ibn ‘Ajrah said: I brought water for a Jew, one date for each bucket, and I accumulated some dates, then I brought them to the Prophet (peace and blessings of Allaah be upon him) … 

Al-Haythami (may Allaah have mercy on him) said:  

It was narrated by al-Tabaraani in al-Awsat and its isnaad is jayyid. 

Majmoo’ al-Zawaa’id wa Manba’ al-Fawaa’id (11/230). 

It was classed as hasan by al-Albaani in Saheeh al-Targheeb wa’l-Tarheeb (3271). 

The fact that the number of potential visitors is unknown at the time when this rental contract is drawn up does not affect the validity of the contract, because this uncertainty will eventually be resolved.  

Based on that, if you rent this permissible website on a monthly or annual basis for a fixed price, that is permissible, even if the rental contract is based on the number of visitors to their site that is advertised on your site, provided that the price per click is fixed, and so long as another important condition is met, which is that you do not use a program to increase the number of people entering the site or hire someone to enter the site repeatedly, so as to increase your benefit from the site that you are advertising. If you do that then you are sinning, and the money that you get in return from that site is haraam to you, and you have to give it back to them. 

Many big companies have taken well-known international websites to court and accused them of falsifying the numbers of visitors to their ads. It says in the al-Jazeerah newspaper (issue no. 113, Sunday 22 Rabee’ al-Awwal 1426 AH: 

It was reported that distorting the figures for response to ads on the basis of “payment per click” is regarded as a serious problem faced by the information technology industry on the internet, because some people –  including competitors or workers who have grudges against their company – click more than once in a continual fashion on the ads, to increase the size of the advertiser’s bill. This may cost the advertisers a lot of money, and it is difficult to trace or stop the perpetrator. 

The statistics of the non-profit Seembo foundation indicate that between 36 and 58 per cent of advertisers feel very anxious about distortion of the figures, but they cannot always catch the perpetrators. End quote. 

For more information please see the answer to question no. 98817. 

And Allaah knows best.