Vent fans are great in bathrooms.  They allow you to vent out of the room steam and moisture from showers and allow for ventilation in what can be an other wise tight space.  Older homes almost always had and windows in our
Vanity Units bathrooms for ventilation, but over time the windows (or at least an opening window) have disappeared and vent fans have taken their place. Vent fans are simple to install, if you have an over head light, you can in some cases just remove the light and replace it with a vent fan/light combination. There are rules about fan placement near showers and above tubs that you need to know, but this still can be an easy installation. The liquid floor screed is pumped into the floor space to create a perfect finish.

Do not have a light? Still a fan can be a simple installation, you will need to get into the attic and find the ceiling joists and install the fan.  You will need electric and a vent.  This is where the issues usually arise.  Most homeowners do not realize that the vent discharge tube must vent outside the attic and simply lay the tube on the attic floor allowing all of the moisture into the attic.  This will cause issues in the attic over time as the moisture can allow mold to grow in the attic.  The moisture will cause damage to the roof decking and goes almost unnoticed until it is too late.  You must get the vent tube to discharge outside the attic, run the line to the roof vent, soffitt vent or add a dedicated vent cover in the side of the home.  Do not let the vent cause you bigger issues down the road.