Whether you're a single or a retired senior citizen, you need to have life insurance.

4 people who need to have life insurance

It's hard to deny that life insurance has a lot of value. No one likes the thought of losing a loved one, but when the unexpected happens, having a plan in place came make all the difference in the world, especially if the person who passes is a primary income earner.

Yet despite the financial protection that life insurance provides, less than half of Americans have an individual policy, according to polling data from research organization LIMRA.

No matter how young or old you are, everyone should have life insurance, as the guaranteed benefits they provide can help get families through difficult times. And there are at least four types of people for whom life insurance is essential.

Single adults

Approximately 105 million adults currently residing in the country are single, according to the latest estimates from the U.S. Census Bureau. At first it may seem like these unmarried men and women are the individuals who need life insurance the least, seeing as how they don't have a family or spouse to support. But that's not the case, because everyone has parents. For example, if a single man or

"Less than half of Americans have an individual life insurance policy."

woman were to get gravely ill or die prematurely, someone has to come up with the finances for end-of-life costs. Additionally, there may be final expenses that have to be taken care of, like credit card debt or student loans. Life insurance ensures that parents or siblings have the financial resources to take care of these issues.

Primary income earners

The breadwinner of the family helps put food on the table and clothes on family members' backs. Traditionally, men have filled this role, but an increasing number of women now hold this position. An estimated 40 percent of households with children 18 years of age or younger includes a mother who is either the only one bringing in money for a family or makes the most, according to a 2013 survey from the Pew Research Center.

"If anyone in your life depends on you financially, you need life insurance," Marvin Feldman, CEO of consumer advocacy group LifeHappens.org, told CNBC.

Senior citizens

By the time people get to their mid-60s, kids are usually full grown and living on their own, meaning that seniors may only have to concern themselves with retirement expenses. But many grandparents today are financially supporting their grandchildren. Of the 65 million grandparents living in the U.S. in 2012, roughly 10 percent lived with at least one of their grandkids, based on a report from the U.S. Census Bureau. Among other things, life insurance not only ensures that dependents are financially supported after a death, but it can also help pay for college tuition or unpaid mortgage expenses. 

Full-time homemakers

Though the cost of living often requires that both parents be bringing in a salary, many Americans are stay-at-home parents. Based on a recent poll from the Pew Research Center, 6 in 10 adults believe that children are better off when a parent is able to stay home full-time to help raise kids. Whether that person is the father or mother is for parents to decide, but whichever person it is, they should have a life insurance plan in place. Financial experts say the best way to determine how much life insurance to buy is by figuring out what the cost of services are to stay at home, such as for transportation, child care, and home maintenance.

Many employers offer group health insurance plans, but you may want to think about an individual policy instead. For the most part, individual policies tend to be more comprehensive than the kind that's employer-sponsored.