When you are working on a spreadsheet, it can be really irritating if your column titles disappear off the top of the page as you scroll down.
To keep column titles in view all the time, use Freeze Panes.
Click on the view tab to get the Freeze Panes option, and click on the little arrow next to it. You have three choices – to freeze the top row, freeze the first column (useful if you are scrolling off to the right), or Freeze Panes. If you click in to a cell, then choose Freeze Panes, the rows above that cell and the columns to the left of that cell will remain in view all the time while the rest of the spreadsheet scrolls.