Yes.
A workbook in Excel will be Book1.xlsx for versions from Excel 2007 onwards, or Book1.xls for earlier versions.
The default file name for an MS Excel workbook is book1. I suppose because the programmer decided book made sense for a workbook and the 1 represents the first one you save. You can change the file name to whatever you like.
Book1.xls is the default name for a new document in Excel.
It normally calls it Book1, but if there were other new workbooks open already, then it could use Book2, Book3 etc.
The default file name for all versions of Microsoft Excel is called "book1"
Initially it is just Book1 and it will have Sheet1 opened in it first. It only uses those names because no other names have been given. It is the same in other applications, like having Document1 in Word for example. When you go to save the Excel Workbook it will give you a chance to give it the name you want or else it will save it as Book1. When you are saving a workbook, or any kind of computer file, you should give it a proper name.
An Excel work book is generally called Book1 before it is named. If there are multiple sheets that have not been named, they will be named the next available number, for example one could have and Book1 and Book2.
A default filename is a name given to a file if you do not choose your own. In Excel the first default filename used is Book1.xls and your file will be called this if you don't specify another one.
It will save it with the name you specify and as the default type of workbook for the version of Excel you have. You should give the file a name, but if you don't it will call it Book1 and then add the appropriate extension. For the more modern versions, which is Excel 2007 onwards, that would be .xlsx, but if you are using an older version than Excel 2007, then it would be .xls instead.
I believe it is Book1
A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.A workbook contains worksheets, which are Excel's name for spreadsheets. A workbook normally has at least three worksheets in it, though more can be added or some can be removed. So in Excel, a workbook is the name of the file and it contains individual spreadsheets or worksheets.
Give each workbook a different name.