Close to your heart.
A declaration of your loyalty.
It is often the custom in a karate dojo for a crest to be worn on the upper left side of a students gi. The dojo crest can vary in shape, size, and colour. Within the body of the crest there might be found, images, symbols, words, or kanji. Taken all taken together they will form a visual representation unique to that particular organization.
This crest may represent a small dojo which is unaffiliated with any local, or international karate organization. On the other hand the dojo crest may represent a much larger organization, headed by a well-known Master who has affiliated dojos around the world. If this was the case then that dojo crest will likely be recognizable world-wide by a global enrolment that could easily number in the tens, if not hundreds of thousands.
Regardless of a dojos affiliation, or lack thereof, by wearing your clubs crest you honour your dojo, and it's traditions. Just like millions of other karate-ka the world over.
Remember: "Your crest is more than just an image, it says, this is my karate family."