What is the ruling on signing up for and participating in Facebook?
Question

                What is the ruling on Facebook?.
Praise be to Allah.Firstly: 
The website Facebook was founded by Mark Zuckerberg, a 
    student at Harvard University in America, at the beginning of 2004 CE. Use 
    of the website was initially limited to students of the University, then the 
    network expanded to include other universities in Boston, and eventually to 
    include the entire world at the end of 2006 CE. 
The aim behind the founding of this site was to enable 
    people to get to know one another and build social relationships. This site 
    is regarded as one of the most important virtual communities on the 
    Internet. 
Secondly: 
The world of Facebook is a world in which one may 
    communicate in writing or verbally (chat), in which there are both major 
    sins and benefits for people, but this site is distinct from others in many 
    ways, including the following: 
1.
Availability of detailed personal information about 
    users, which has already resulted in negative consequences such as: 
(a)   It has led to reviving old 
        relationships between lovers which led to a resumption of those 
        (illicit) relationships, leading to betrayal and divorce. 
A team from the National Centre for Social and Criminal 
    Research in Egypt prepared a study on Facebook which took several weeks, 
    from which it noted serious consequences (of using this site). Among other 
    things it noted: “many visitors to the website succeeded in finding their 
    first love and former relationships, and rebuilt destructive relationships 
    outside the family, which is threatening marriages and Muslim family life.” 
A foreign newspaper discovered a Jewish spy network that 
    was working to recruit Arab and Muslim youth to spy for them.
 On the Muheet website – dated 25 Jumaada al-Oola 1431 AH 
    – they quoted from a French newspaper the story of Jewish exploitation of 
    Facebook to recruit agents: 
Gerald Nero, a professor in the college of psychology in 
    the French University of Provence and the author of the book Dangers of the 
    Internet, says: “This network was discovered in May 2001 CE; it was a group 
    of networks run by Israeli specialists in psychology who were recruited to 
    work on youth in the Third World, especially those living in Arab states 
    that are hostile towards Israel, as well as South America.” 
In fact, this recruitment began before the founding of 
    the Facebook site, which offered more opportunities for this network – and 
    others like it – to find youth who were suitable for recruitment by looking 
    at their details and by chatting with them. 
(b)   Hacking into bank accounts and 
        stealing the identity of a Facebook member by looking at his personal 
        information. 
2. The spread of this website has made it a global chat 
    site which brings together people from all parts of the world; they made 
    matters worse by giving the users of their site a program that makes it easy 
    for these conversations to take place without entering the site, such as 
    that which was produced by Hotmail and Messenger. Chatting results in 
    negative consequences that are known to everyone who has any experience of 
    that on the Internet, especially if the program makes it possible for people 
    to see one another as well as writing. Among the negative consequences of 
    chat and sinful relationships are the following: 
(a)   Wasting valuable time in trivial talk 
        and getting to know people. 
The wise Muslim should realize that his lifespan is 
    limited and that he will not live on earth for ever; he is going to meet his 
    Lord, may He be exalted, Who will ask him about his youth and how he spent 
    it, and about his life and what he did. So let the wise one look at the 
    early generations of this ummah and its scholars, and think about how they 
    thought about time and their lifespan. 
Ibn ‘Aqeel al-Hanbali (may Allah have mercy on him) said 
    of himself: It is not permissible for me to waste an hour of my life. When I 
    stop discussing issues of knowledge and debating them (with others) and when 
    I stop reading in a book, I would start pondering and thinking when I am 
    resting and lying down, and before I get up, I will have already an idea 
    that I should write down and I am very keen to increase my knowledge now I 
    am in my eighties and more keen than when I was twenty years old. 
Quoted from him by Ibn al-Jawzi in al-Muntazam, 9/214 
Ibn al-Qayyim (may Allah have mercy on him) said: A man’s 
    time is in fact his life, and his eternal life, whether it is eternal bliss 
    or eternal suffering, is based on how he spent it. Time is passing quickly; 
    whatever time he spends for the sake of Allah and by the help of Allah, this 
    is his true life; any other time is not counted as part of his life, even if 
    he spends it doing what animals do. So if he spends his time in 
    heedlessness, idle entertainment and false wishes, and the best of what he 
    spends his time in is sleep and idleness, then his death is better than his 
    life. 
Al-Jawaab al-Kaafi, p. 109 
(b)  Establishing sinful relationships between 
        men and women, which may cause the destruction of a stable family. 
In a study by the National Centre – mentioned above – it 
    says: 
One in every five cases of divorce came about when one 
    partner discovered that the other was having a relationship through the 
    Internet, and through Facebook. 
We have discussed the ruling on correspondence and chat 
    between the sexes in a number of fatwas. Please see the answer to questions 
    no. 78375, 34841, 23349,20949, 26890 and 82702. 
    Thirdly: 
It cannot be denied that there are a number of benefits 
    in this site, which are attained by wise people who are keen to guide people 
    to goodness. These people have done well by using modern means of 
    communication – such as the Internet, mobile phones and satellite channels; 
    they have entered the world of those people to serve their religion and call 
    people to their Lord, especially activities that are done collectively, 
    because that makes it less likely that the one who does this type of work 
    collectively will fall into the temptations of that world. Among the 
    benefits of that website are the following: 
1.     Personal pages for some 
      shaykhs and daa‘iyahs, in which they offer advice to the people and answer 
      their questions, especially those who have groups. The leader or founder 
      of the group benefits when a number of people who are part of that group 
      get together and send out messages to the group, open up topics for 
      discussion, and post a large number of high-quality video clips.
2.     Global campaigns to alert 
      users of that site to global Islamic events that are suppressed and 
      ignored by the non-Muslim media, or to support oppressed peoples, or to 
      close a website or personal page.
3.     Spreading useful and 
      beneficial books, articles and websites among visitors to that site.
4.     Communication between 
      friends and relatives, especially those who live far apart from one 
      another. Communication has a good impact in maintaining bonds and 
      encouraging one another to remain steadfast in Islam.  
Fourthly: 
With regard to the shar‘i (religious) ruling on signing 
    up for Facebook, it depends on the intention of the one who wants to sign 
    up. If he is a man of knowledge or a seeker thereof or a member of a da‘wah 
    group, then it is permissible and good, because of the benefits they have to 
    offer to the people. But for the one who joins it for evil purposes or for 
    whom there is no guarantee that he will be safe from temptation and may 
    easily slip, especially young men and women, it is not permissible for them 
    to sign up for it. 
The one who knows the reality of our times and the 
    temptation and turmoil that is knocking at the door of all of our houses 
    will not object to any faqeeh or mufti (religious scholar) who disallows 
    anything in which there is harm, whether it is totally or mostly harmful. 
    The fact that there is some small benefit does not encourage one to say that 
    it is permissible because there is still fear for the one who embarks upon 
    it. If what is good and beneficial is great and the evil and harm is small 
    or non-existent, then we may with a clear conscience say that it is 
    permissible. Hence some of our scholars were very strict about satellite 
    channels at first, because of the pure harm and evil in them; but when there 
    started to be some great good in them and completely Islamic channels were 
    founded, and receivers that only accepted those channels became available, 
    the view that they are permissible became valid; indeed we see that many 
    scholars have contributed to these channels and have useful programs on 
    them. 
The one who cannot control himself on Facebook and 
    similar sites should refrain from joining them. Joining them is permissible 
    for the one who acts in accordance with the shar‘i guidelines by controlling 
    himself and not following his whims and desires, and who joins them  so 
    that he can benefit himself and others.
We ask Allah to keep us safe from temptations both 
    visible and invisible, for He is the Guide to the straight path. 
And Allah knows best.