File extension - in simple words, it is a sequence of several symbols that allows you to determine what type of data is stored in the file. The file extension appears after the last dot in the file name, ex. sampleFile.doc

In order to open a file with an unknown extension, it is necessary to install appropriate software that can read the data stored in your unknown file.

There is no one all-purpose software to open each file type. Most file types have an individual data structure, and in order to open such a file correctly, we need software that will be able to properly interpret the data stored in it.

Yes. There may be situations where one file extension can be assigned to different data types. For example, many programs use the .DAT file extension - it does not mean that the data in these files are organized according to one standard. To open such a file, you need the program that created it.