Depression is the most common mental health issue in the UK. Around the world, it affects an estimated 350 million people.
With this in mind, it's surprising how behind we are - as a nation (and globally, too) - in our knowledge of what depression actually is and how it can affect people.
With stigma of mental health in the workplace being a huge issue - just look at the Time To Change campaign if you need further proof - it's no surprise that those who suffer from depression sometimes get frustrated by the widespread lack of knowledge surrounding the illness.
To tackle the problem head on, here are seven incredibly important things that people with depression want you to know.
1) Depression is not a stereotype. Anybody can have it
In her blog post on coping with depression as a teen, Elise Jamison writes: "Anyone can have depression - from celebrities, to hairstylists, to that guy next to you in algebra. It isn't just the gloomy kids.
"This illness is pervasive and the amount of misconception is astounding."
2) It is not "sadness"
"In my experience depression is very different from sadness. It is the absence of feeling.
"When you are sad you feel something. Sadness can be a release. Grieving over the loss of something helps you to come to terms with it, feel the emotion and move on," she says.
"Depression is a loss of emotion, the very thing that makes us human. It is a state of limbo in which everything you have ever known no longer makes sense or has a purpose."
3) Depression is not something you can relate to
Blogging for HuffPost UK, Jamie Flexman says that depression is not relatable: "How many of you have a tail? You know, like a monkey. If you haven't (which I hope is everyone), can you imagine what it is like to grip a branch or maybe just swing it back and forth? It's impossible isn't it?
"Depression is similar to that. If it's something that you have never experienced then you can try as hard as you want, but you will never truly know what it feels like."
4) Don't assume people with depression want to talk about it
"One of the most challenging symptoms of depression for those around you, is that you don't want to talk about it," writes Tayana Simons.
"In truth, you don't know what is wrong, and when people ask you, trying to explain it makes you feel foolish and guilty for wasting their time.
"The benefit of hindsight allows you to see that things can, and do, change, but when you are in the middle of that valley you can't see over the mountains to any kind of horizon."
5) You can't just "snap out of it"
Offering an insight into what depression feels like from a sufferer's perspective, Jamie Flexman writes: "When depression has its grip on you, life becomes water. The air around you becomes water, crushing you with its weight and even the simplest tasks become difficult. You feel sluggish, both mentally and physically and nothing can snap you out of it."
He adds: "You have essentially become trapped inside your own prison and true access to your brain lies behind that locked door. Sometimes, briefly, you are allowed outside to stretch your legs but you know this is temporary.
"Eventually you will have to return to your cell and wait patiently for a time when you are given another opportunity to function like a normal member of society."
6) If someone with depression has a "good day", it doesn't mean they no longer have depression
Danny Baker blogs on HuffPost UK that when people with depression have a "good day", people assume that it means they no longer suffer from the illness.
"People with depression can have 'good' days where they don't feel depressed - indeed, they can have days where they even feel happy," he writes.
"But it's a mistake to assume that just because they feel good one day, that they're no longer sick and therefore should feel good every day.
"Depression just doesn't work like that."
7) It doesn't last forever
"Like even the fiercest of storms, with the right help and support, it will pass eventually," writes Tayana Simons.
"Although you may never be the same as you were before, you will be a new you, stronger and more self aware.
"The biggest lesson that I ever learnt was to let people help me, even when it felt like the most unnatural thing to do."