This is a system that my own company used to find a development company to build. Now we need to do some functional expansion, but the original development company has collapsed. I have some front-end basics, HTML, CSS, and JS. I should be able to do it. I also know a little bit about CentOS and SQL, but I have never been exposed to PHP. I want to do it myself. Is this developed in PHP5.5? Is this too old? Is it possible to make changes after learning php7.0 or 8.0? Is it made using those open source frameworks? 
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
If you want to change, it is recommended to learn 5.5~ There is still a big difference between 5.5 and 7
If you want to learn something new, just refactor it. The version span of php8 is still too big