http://en.wikipedia.org/wiki/Nebulizer
The most commonly used one is what is called Jet Nebulizer (see section in above).

Use depends on the medication and what a doctor has prescribed. (Although there are some that mix their alternative or home brew herbs, and such.)
For example, I use one twice a day for inhaling Budesonide and Brovana, with an occasional extra applications of Abuterol. The latter usually only for a few days when bronchitis or a flare-up is a problem.

This goes into the relative advantages and disadvantages of various COPD inhalers:
http://www.webmd.com/lung/copd/how-copd-devices-work

That should answer most of your questions.

I use a nebulizer with Albuterol usually at least once, and
sometimes twice a day.

It cuts down ...for me at least....the number of times I need an
emergency inhaler by quite a lot.

Worth a try if you need rescue inhalers on a daily basis.

i have the "aeronebgo" as it just seemed more compact and easy to clean that the regular nebulizer.
the nebulizer is just the machine that you pour the prescribed medicine into that heats it to become a mist.
i find mine is much better at getting deep into my lungs when i am having an exacerbation or hard to inhale deeply days.
the medicine i was perscribed for mine can be used 4 times a day. so always follow your dr's instructions.
i;m not sure if this link will work for the images or not;
https://www.google.com/search?q=aeroneb+go&tbm=isch&tbo=u&source=univ&sa=X&ei=0JHPVP7VEYb0oASi7ILIAw&ved=0CGgQsAQ&biw=1366&bih=588#imgdii=_&imgrc=i1936iuHVMiC-M%253A%3B6BJVocL3THEyNM%3Bhttp%253A%252F%252Fcdn3.volusion.com%252Fj575u.gtsw7%252Fv%252Fvspfiles%252Fphotos%252FAeroneb-Go-3.jpg%253F1408445279%3Bhttp%253A%252F%252Fwww.phc-online.com%252FEVO_Nebulizer_p%252Faeroneb-go.htm%3B400%3B400
i use a once a day inhaler of spiriva & the nebulizer with "albuterol" my rescue because i couldn't seem to do the "puff" inhalers.... so it also depends what medication your dr prescribes for it to how often you do it & how well it will work for you.

The nebulizer is a method of taking meds that seems to me to get it way down in my lungs better. I use albuterol, and can be used every 6 hours as needed. They are great to use when you are bad conjested, or when you are trying to get the airways open and the inhalers are just not getting it.

I do not like to do to much because Albuterol is stimulant and will have me jumpy if to much.

I do 1 nebulizer with albuterol when i get up every morning. It is great way to open your up and loosen the goop of mucus that collected over night. It last for about 6 hours.
.
15 to 30 minutes later I do my Spariva which is a 24 hour bronchodilater, ,

The15-30 minutes after that I do my symbicort which I use every 12 hours and has steroid in it.

Go by what ever the doctor has ordered, and as many times he has ordered it. If he wants it used several times during the day, ask him about the other inhalers you will be taking with it.

I requested a nebulizer for home use the first time shortness of breath brought me to the ER. I use it first thing in the morning as it does a great job opening up my lungs for other medications. My prescription is for up to 4 x daily - but for me, if I need it that often, I am in trouble and should be on prednisone and antibiotics.

Thanks for all the info!

it delivers a mist to your lungs and lasts anywhere from 4-6 hrs depending on your symtoms..im on it more now than ever..its good but always rember to use your rescue inhaler..it takes 5 min to work and lasts about 2 hours.