If you're lonely, it's certainly not lonely.

Have you ever wondered why you feel lonely, even when you're not alone? I know it sounds like a pretty depressing topic, but hear me out: Loneliness is a real emotion, and studies show that if you're feeling lonely, you're certainly not alone. In fact, a 2014 study released from Relate shares that one in 10 people feel they do not have a single close friend, which breaks down to about 4.7 million people. That's a pretty high number, and a sad one, too.

Of course, the tricky thing about emotions is that they're different for everyone: Some people, for example, are perfectly fine having few friends, or enjoy spending a great deal of time alone. For other people, those same scenarios would create a deep sense of loneliness and isolation. If you enjoy being alone, that's great! There's no need to create a tension when you're happy with a situation.

That said, loneliness can have serious effects on your mental and physical health. For example, experiencing chronic loneliness can lead to a higher risk for dying of heart disease, weaker immune systems, and consuming less healthy foods, like vegetables. Loneliness can also hurt your sleep patterns, increase your risk for developing dementia later in life, and may even contribute to early death.

There seems to be a strong stigma about loneliness. Many people will admit to being depressed before they'll talk about being lonely. They fear being judged as unlikeable, a loser, or weird so they don't discuss their sense of aloneness, alienation, or exclusion.
Not feeling free to talk about loneliness adds to the problem and to the judgments of the experience. If you judge yourself for feeling lonely, it makes it even more difficult to take steps to change the situation. Then you may judge yourself for not taking action to solve the problem.

That horrible experience of being the last one chosen for teams in school seems to continue into adulthood, though the reasons are different. The general idea seems to be that if you don't have friends, then there must be something wrong with you

Loneliness is a different experience than solitude. Solitude is being alone by choice and wanting that aloneness or being comfortable with it. Loneliness means there is a discomfort-- you want to be more connected to others.
Many people are lonely even though they have acquaintances and activities. Having hundreds or thousands of "friends"  on social networking  websites isn't the same as having someone to share a movie or to get a cup of coffee. One of the loneliest experiences may occur when you are in a crowd of people you do not feel connected with or when you are with a life partner/friend and feel no connection.
Being lonely seems to be about not feeling connected in a meaningful way to others, to the world, to life.