I am building a small and very simple web app for users in a company. It's built on vanilla PHP and MySQL, no frameworks and it is very lightweight. I am new to hosting and I'm wondering if Amazon Lightsail would be a good solution for hosting everything. I think EC2 and RDS would be too excessive for what I am trying to accomplish. What is the best way to go about hosting the PHP and database?
Lightsail is just EC2 and EBS with a different name, packaged up, and maybe a touch cheaper. You can run your app on LightSail - just install Ubuntu, PHP7, and MySQL, which will no doubt be easy to do via some method or other.
AWS EC2 + EBS + RDS will be more flexible and higher performing, and if you think you'll end up with that it's probably easiest to start with it. However you can start with LightSail then add RDS or any other AWS server you need.