Nowadays android has got a majority over other OS on mobile devices. Sometimes we can see the UI i.e. user interface of android looks dull. So some developers customized the default OS to the new look, which gives the opportunity to explore brand new designs and features.
ADVANTAGES OF CUSTOM ROMS
1. New launcher.
2. New icon pack.
3. System updates for older phones.
4. More free RAM and faster phone.
5. More customization option.
6. Administrative access or root access.
DISVANTAGES OF CUSTOM ROMS
1. They void warranty.
2. Lack of google application.
3. Maybe less secure.
EXAMPLES OF CUSTOM ROMS WHICH ARE POPULAR