Blood clots are clumps created by blood cells and fibrin strands to stop bleeding after a blood vessel got damaged. These are protective scabs over damaged blood vessels. Without these, even minor wounds would cause your death because of bleeding. Any form of wound in the body would initiate the clotting process.
Platelets are the ones behind these. They release chemicals which help and improve blood clotting in the body. The clot would usually stay in place until the healing process is done. Other chemicals will be responsible for it after it heals.
These clots are usually caused by a number of factors that ranges from daily routines to genetics. The most common of them are:
i) If you have any kind of cancer.
ii) If you had surgeries before especially heart surgeries.
iii) If you are obese.
iv) If your family has history of blood clots.
v) If you are not doing something for a long time. (e.g. sitting in a plane for plenty of hours)
vi) If you have been fractured or hurt to the extent that you undergone surgeries etc.
vii) Changes in normal blood flow.
Blood clots are most of the time dark purple or red when they are outside our body. They are just a drop of blood that has clustered together. In the first stages, clots can only be seen as red lines that may also cause pain due to swelling. A blood clot can also appear like a scab on your skin whenever a cut or an injury has stopped bleeding. However, if the clot is an inside your body, it cannot be seen with the eye.
A doctor should use specialized machines to find the clot inside your body. There usually no symptoms for internal clots that is why regular check-ups are a must.