A table cell is one grouping within a table. Cells are grouped horizontally (rows of cells) and vertically (columns of cells). Usually information on the top header of a table and side header will "meet" in the middle at a particular cell with information regarding the two headers it is collinear with.
Kinds of cell in HTML
A table cell in HTML is a non-empty element and should always be closed. There are two different kinds of table cell in HTML: normal table cell and header cell. <td> denotes a table cell, while <th> denotes a table header. The two can be used interchangeably, but it is recommended that header cell be only used for the top and side headers of a table.
A table cell also must be nested within a <table> tag and a <tr> (table row) tag. If there are more table cell tags in any given row than in any other, the particular <tr> must be given a colspan attribute declaring how many columns of cells wide it should be.
An example of an HTML table containing 4 cells:
|Cell 1||Cell 2|
|Cell 3||Cell 4|
<table border="1"> <tr> <td> Cell 1 </td> <td> Cell 2 </td> </tr> <tr> <td> Cell 3 </td> <td> Cell 4 </td> </tr> </table>
Colspan and Rowspan
Every row must have the same number of table data cells, occasionally table data cells have to span more than one column or row. In this case the tags colspan and/or rowspan are used - where they are set to a number.
|<-- This row has three table data cells|
|<-- This row has two. The first uses
|<-- This row has three table data cells, but one spans two rows because it uses
|<-- This row has only two table data cells, because its first is being taken up|