When Sheryl Sandberg, the chief operating officer of Facebook recently posted a heartbreakingly moving piece about her husband who had suddenly died, she noted that she was writing to mark the end of the traditional Jewish 30-day mourning period, the shloshim. In so doing she probably increased by tenfold the number of people who had ever heard of this concept.
Shloshim is a less intense period of mourning than the seven days of shivah. It marks the end of the mourning period for all close relatives apart from parents, whom one mourns for 12 months. During the shloshim, many of the halachic restrictions of the shivah period are relaxed; one may go back to work, learn Torah and resume marital relations, for example. Others remain in force; if in doubt, consult your rabbi.
The gradual lifting of mourning for a relative and returning to full involvement in life is paralleled and reversed during the three weeks of mourning for the Temple that we are now in, during which mourning ascends in gradations culminating in Tishah b'Av.