Social security in Sweden
Social security in Sweden is one of the parts of the Swedish welfare system and consists of various social insurances handled by the National Agency for Social Insurance (Swedish; Försäkringskassan), and also welfare given out on a need basis by local municipalities. They are the main conduits for redistribution of approximately 48% of the Swedish GDP in the form of taxed income.
Child allowance and parental benefit
The parents of children up to age of 18, receive a child allowance, "barnbidrag" of 1,050 kr per child, with an additional supplement, "flerbarnstillägg", for multiple children ranging from 1500 kr for two children to 4,114 kr for six children. The parents also receive parental benefits, "föräldrapenning", to be able to be home from work to take care of their children for up to 480 days, and a temporary parental benefit to stay home and take care of a sick child. The levels depend on income. There is also a childcare allowance, "vårdbidrag" to enable parents to stay home and care for children with long-term illnesses.
Families with children, and people below 29 years of age may be eligible to receive a housing allowance, "bostadsbidrag". The amount depends on income, the size of the family, housing costs and house size. At most it is 1.300 SEK. 
Benefits for ill and disabled
Working people are entitled to sick pay when ill. The first 14 days (except the first day off) are paid by the employer, the rest by Försäkringskassan. If an employee's ability to work is permanently reduced, disability payments may be made.
If you need time-consuming assistance in your everyday life to be able to work or study due to illness or disability you can obtain disability allowance, "handikappersättning". If you have a substantial and permanent disability where you need assistance with mealtimes, washing, clothing and communicating with others, you can receive an attendance allowance, "assistentersättning", to pay for an assistant. If you have great difficulties in getting about on your own, or in using public transport due to a permanent disability you can obtain an allowance to purchase a car, make alterations to a car, and to take a driving licence.
Support for the elderly
If you have worked in Sweden and earned a taxable work income, you will be entitled to Swedish old age pension, at the earliest from the age of 61 years. The levels depend on your income and how long you have worked. There is also a guarantee pension which you are entitled to if you have lived for at least three years in Sweden if you have had no or low income. Elderly can also receive housing supplements or maintenance support. The levels of these depend on your needs. 
If you have no or low income you can apply for welfare from your local municipality. The municipality will look at your economic situation to determine if you should receive welfare or not. The welfare should be enough to cover things like housing, food, clothing and telephone.