Real estate investment can happen for various reasons. You could invest in real estate because you need a house for yourself (that house of your dreams that you so badly want). You could use real estate as a means for supplementing your income either by buying at a lower price and selling at a higher price or by letting it out. Sometimes you might buy a property for the purpose of resale but might want to wait for a few years before you actually sell it. In such a case, again it would make sense to rent out the property and earn some money till you actually decide to sell it off.
Whatever the reason, letting out real estate demands real estate management and real estate management is not an easy job for everyone. In fact, a lot of people find it so much of a hassle that they prefer keeping their property vacant instead of letting it. Real estate management demands time, which you will rarely have. Real estate management is not just about finding tenants and collecting rent from them. Real estate management is also about ensuring that you do all the duties that a landlord/landlady is required to do. Real estate management is about verifying the credentials of the tenants before you actually let out your property to them.
Real estate management is about ensuring that all the paper work is complete and correct i.e. the tenancy agreement etc are properly done. Real estate management also requires you to do repairs as and when required. Real estate management activities also include maintenance, painting, polishing etc of the house when the tenants move out and before the new tenants get in. So, really, real estate management is not that easy a job for someone who is in a full time job. However, there is a solution to this and that is hiring a real estate management firm to do all these activities on your behalf.