What is considered to be normal Vaginal discharge? When does it become a cause for concern? Please explain

Vaginal discharge is normal and it is important for lubrication and also protects against infections, because of antibacterial properties.  

It is a discharge from the vaginal and cervical glands and is normal, if it happens before ones period, after periods and mid- menstrual at the time of ovulation. Normal vaginal discharge is usually mucoid in nature and does not have any foul smell.

But if the discharge is excessive and one has to use a pad, it is abnormal and also if the change in colour happens along with a foul smell, or if it is associated with itching. Thus, if any of these aspects are present in vaginal discharge, it needs immediate attention and examination by a gynaecologist and treatment as well.