Wound vs unwound strings and when to tune the 'ukulele.

I am sure this has been posted before, but what are wound and unwound strings? Why should I choose one or the other?

Also, I have had my same uke strings (Aquila) for 5 months and I feel they have lost the crispness in sound they initially displayed (in about two months of use) and I'm finding myself tuning them more and more often. Am I just imagining that or...? *I play about 2 hours a day.

One last question: What is a good brand of 'ukulele strings with a low G that would somewhat resemble the sound Bruddah Iz made with his uke in Somewhere Over the Rainbow?

Thanks and sorry if I am asking questions that have already been asked!

If you play for around two hours a day and you have had the same set of strings for 5 months, it is a pretty safe bet that you need a new set of strings. The change in sound quality is not your imagination. Wound strings have a metal winding around a solid core to increase the diameter and mass of the string, so you can tune it to a lower pitch than a plain string. Look at the three bass strings of a guitar, for example. Most of your low G strings will be wound. What brand of strings to get is purely personal preference, I don't know what Iz used.

Brad

I wouldn't recommend that you wait 5 months to change your strings again. Recording musicians will often change strings daily during recording sessions.
Be conscious of the sound of your strings and change when whenever they are dull. Be willing to try new things too. Different strings exist for you to try them. Go ahead and try a wound C string, or a low (or also wound) G string. Many people here, or anywhere for that matter, will have different opinions.
Music is about doing it for yourself!