when you upload files, you can then get the necessary data from $_FILES files contains the list of file inputs, where each one has a field like [type]

örneğin:

Array
(
    [file1] => Array
        (
            [name] => 'MyFile.txt'
            [type] => text/plain  //where does this come from?
            [tmp_name] => /tmp/php/php1h4j1o
            [error] => UPLOAD_ERR_OK
            [size] => 123
        )
)

does it come from within the file, or the file extension, or somewhere else? how does php get the type? where does the [type] come from and can I trust it as valid?