Under Perens' definition, open source describes a broad general type of software license that makes source code available to the general public with relaxed or non-existent copyright restrictions.
1 Illnesses such as the flu or colds. Home treatment of your flu and cold symptoms usually will relieve lightheadedness. 2  Vomiting, diarrhea, fevers, and other illnesses that cause dehydration.  Very deep or rapid breathing (hyperventilation).
Heart Attack. Heart attack is one of the more serious conditions that cause lightheadedness. During a heart attack, oxygen is prevented from getting to the heart and the rest of the body when blood vessels are blocked, causing the head to feel light and weightless.