Advantages of Double Sided Pcb：

Double sided pcb boards are a common tool in both production and prototype circuits. They allow a higher density in components and make laying of tracks an easier process.

Same as a regular circuit board, Double sided circuit board are made with a substrate of non conductive material, over which a layer of copper is placed on top of it, and in the case of double sided boards, the copper is also layered on the bottom side of the substrate.

As with any type of circuit board, there are advantages to the use of one type over another.

Double sided pcb boards,  allow a higher density of component. This is because you have a whole extra layer where you can add tracks to connect the components, freeing space on the other to place the components closer together or add extra connections for IC with high pin counts.

Another advantage of using double sided pcb boards  is the increased heat dissipation that an extra layer of copper provides, this can be achieved in the etching process, only removing enough copper to create the tracks, leaving the extra copper instead of removing it completely.