These patterns are symbols that were originated from the ancient Celtic people, who did not have any form of written language. Most of this ancestory came from cultures in countries such as Ireland, Wales, Scotland, and Great Britain.
Going back thousands of years these people showed their skills in forms of art such as their jewelry, metals, weapons, carvings, etc. Today its thought that tats on these people begun around the same time thousands of years ago.
These images are very distinguishable among many other different forms of art with its interlacing patterns, bewildering knots, animal figures, and assorted symbols only known to people of this ancient world. These old patterns and symbols all have a significant meaning among these cultures.
So when deciding a design for yourself make sure you’ve studied and are fully aware the meaning behind the image. If you are one of Celtic heritage (Scottish, Irish, Welsh, etc) then this type of ink may be used to express pride and belief in your heritage. 
Celtic knots and the cross are the two most popular forms of this design. The knot is supposed to be an endless knot with no beginnings or endings, and is known as the “mystic knot.” This pattern may be used to symbolize that there is no beginnings or ends to life. A reminder to these people of the timeless nature of the soul.
Again remember that different knots have various meanings as well, and also may be very hard for an artist to draw up the exact way you want it. Make sure when choosing an artist to draw up your tat that this person has had experience in the past with these type of designs. If one screws up a line, or maybe draws one too close together, it may be nearly impossible to fix.
Same goes for a Celtic cross tat this type of pattern should also be done by a professional with experience in this field. This cross was also known as the “wheel Cross” or “Ring Cross” in the Middle Ages. Many years ago this cross may have been used to symbolize fertility. Simply with the cross(plus sign) standing for the male and the inner circle standing for female. Today this image is commonly used to symbolize ones belief in his/her religions such as Christianity.
So if you are maybe firm in your beliefs, or possibly one from the Celtic cultures this type of ink may be right for you!
