You might decide to have a theme party for any reason, birthday, anniversary, promotion or anything else maybe just to celebrate and break the monotony. Having a theme helps in planning in one direction and not running here and there thinking of decoration, games etc.
The theme need not be a great one it could just be a very simple one like “Black and White”. You could choose the theme depending on the reason for the party audience for the party or likes of the person for whom you are celebrating the party.
Most of the people feel that everything at the party needs to adhere to the theme, but you need not be so strict. As far as some of your decoration, games and gifts is based on the theme it is ok. You can try to add in theme based dress code or entertainment or the cake etc but that totally depends on you and your planner.
More or less there are three types of themes:
Character party theme: This is based on one character popular within the age group, this is especially good for children. Superman or Mickey Mouse party etc. Next is the
General theme: This is very general concept like the ocean theme, red party etc.
The last one is the timeless themes which are based on an idea e.g. the cricket theme, movies theme. These are generally easy to plan as these are very flexible, lot of options are there and can fit into any budget.
You could ask for the party theme from your planner or the local store or decide on it impromptu, such themes might be little off the league and it might be difficult to find suitable decoration etc but creativity is the key. You can make a theme out of any party idea and plan the arrangements around it.
To choose an appropriate party theme you need to consider your budget, space and add your imagination. Who knows your creativity with fresh ideas for party themes might make your parties talk of the town.