Your frame's aspect ratio is more than a mere relationship between its width and height.
Choosing your film's aspect ratio may be something you've never really thought that much about. In fact, you might have always just stuck with your camera's default setting, whether it's 2:40:1, 4:3 or 16:9. However, being wise about which aspect ratio you go with is not only important for distribution but it can also add a lot of depth and visual appeal to your projects. In this video, Zach Ramelan of PremiumBeat goes over how to choose the right aspect ratio for your films and videos. Check it out below:
There are many reasons why it's important to make informed decisions about your projects' aspect ratio, but the two at the top of that list are 1.) method of distribution, and 2.) aesthetics.
Where are you intending to showcase your project? In a theater? On YouTube? On social media? There are many avenues that you could take your film or video down, but knowing where it will end up can help you decide on which aspect ratio you should go with. For example, if you're distributing your film on YouTube or Vimeo, widescreen 16:9 is the standard (though you definitely don't have to settle for it), while most theater screens cater to really any ratio you like, including 2.40:1 anamorphic. Furthermore, if your project is going to be seen primarily on smartphones, you might want to go vertical. Your method of distribution doesn't back you into a corner, but it could help you make a choice on which aspect ratio to go with.
I'm sure you've noticed how many filmmakers add matte bars to give their 16:9 shots a cinematic 2:40:1 aspect ratio. This is because that anamorphic look, as well as 1:85:1, has become synonymous with cinema, so by simply adding a couple of horizontal black bars at the top and bottom of your shots you've already told your audience, "Hey, this is cinematic!" That doesn't mean that widescreen isn't cinematic, though, so you can play around with different aspect ratios to figure out which works best for your project—hell, you might find that vertical video is exactly what it needs.