This tag implies that the bands and artists are Serbian or originated in Serbia. Music represented by this tag is often highly commercial. Other, possibly better, Serbian tags are, for example Novi Val or nova srpska scena.
For how long do I need to wear retainers? It takes time for the bone and all the tissues around your teeth to reorganise and therefore it is necessary to use retainers until your bite stabilises. In the first month after the braces are removed, the risk of relapse is very high.
The way the system works is you wear a set of Invisalign trays (called aligners) for two weeks at a time. Each tray is manufactured so that the teeth are slightly straighter than the previous tray. The teeth will typically move 1/10mm per tray.