How to Put Spacing Between Tbody Elements

Something like this will work, depending on your browser support requirements:

tbody::before
{
  content: '';
  display: block;
  height: 15px;

}

People will always have controversial opinions about using empty table elements to layout a page (as evidenced by this answer's downvote). I recognize this, but sometimes its easier to use them this way when you are working in a "quick and dirty" way.

I've used empty rows in past projects to space groups of table rows. I assigned the spacer rows a css class of their own and defined a height for that class that acted as a top and bottom margin for that group of table rows.

    .separator{
             height: 50px;
    }

   <table>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>

           <tr class="separator" colspan="2"></tr>

           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>

           <tr class="separator" colspan="2"></tr>

           tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
           <tr><td>Cell 1</td><td>Cell 2</td></tr>
   </table>

If you don't have borders on your table cells, you could also define a height to your typical cell or row in your style sheet that evenly spaces out all rows of your table.

tr{
   height: 40px;
}

I had been in trouble spacing properly multiple <tbody> with ::before pseudo, in presence of <tr> containing <td> with rowspan in a couple of browsers.

Basically, if you have a <tbody> structured like this:

<tbody>
    <tr>
        <td>td 1</td>
        <td rowspan"2">td 2</td>
        <td>td 3</td>
        <td>td 4</td>
    </tr>
    <tr>
        <td>td 1</td>
        <td>td 2</td>
        <td>td 4</td>
    </tr>
</tbody>

And you follow who advises to write css on ::before pseudo element like this:

tbody::before
{
    content: '';
    display: block;
    height: 10px;
}

This will affect the rowspan, making table "losing" within the second <tr> how many <td>-rowspan are present in the first one.

So, if anyone encounters that type of problem, the solution is to style ::before pseudo in this way:

tbody::before
{
    content: '';
    display: table-row;
    height: 10px;
}

Here's a fiddle

Here's another possibility that relies on :first-child which is not available in all browsers:

<style>
table {
  border-collapse: collapse;
}

td {
  border: 1px solid black;
}

tbody tr:first-child td {
  padding-top: 15px;
}

</style>

<table>
    <tfoot>
        <tr><td>footer</td></tr>
    </tfoot>
    <tbody>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
    </tbody>
</table>

Of all of the answers given above, only djenson47's answers retain separation of presentation and content. The drawback of the collapsed border model method is that you can no longer use the table's border or cellspacing attributes to separate the individual cells. You could argue that this is a good thing, and there are some workarounds, but it can be a pain. So I think the first-child method is the most elegant.

Alternatively, you could also set your TBODY class' overflow property to anything other than "visible." This method allows you to retain a separated borders model as well:

<style>
tbody {
    overflow: auto;
    border-top: 1px solid transparent;
}
</style>
<table>
    <tfoot>
        <tr><td>footer</td></tr>
    </tfoot>
    <tbody>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
        <tr><td>Body 1</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
        <tr><td>Body 2</td></tr>
    </tbody>
    <tbody>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
        <tr><td>Body 3</td></tr>
    </tbody>
</table>

You can use border-spacing in a table with table row groups to add a space between those groups. Though, I don't think there is a way to specify which groups are spaced and which are not.

<table>
  <thead>
    ...
  </head>
  <tbody>
    ...
  </tbody>
  <tbody>
    ...
  </tbody>
  <tfoot>
    ...
  </tfoot>
</table>

CSS

table {
  border-spacing: 0px 10px; /* h-spacing v-spacing */
}

Just set display as block and it will work.

table tbody{
    display:block;
    margin-bottom:10px;
    border-radius: 5px;
}

Because padding can be applied to TD's, you can do a trick with the + sign. Then it will be possible to give a top padding to the TD's of the first TR of a tbody:

// The first row will have a top padding
table tbody + tbody tr td {
    padding-top: 20px;
}

// The rest of the rows should not have a padding
table tbody + tbody tr + tr td {
    padding-top: 0px;
}

I have added the "tbody + tbody" so the first tbody won't have a top padding. However, it's not required.

As far as I know there are no drawbacks :), though didn't test the older browsers.

NEW ANSWER

You can use as many <tbody> tags as you like. I didn't realize that was ok by W3C until now. Not to say my below solution doesn't work (it does), but to do what you're trying to do, assign your <tbody> tags classes and then reference their individual <td> tags through CSS like so:

table tbody.yourClass td {
    padding: 10px;
}

and your HTML thusly:

<table> 
<tbody>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
<tbody class="yourClass">    
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
<tbody>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
<tr><td>Text</td></tr>
</tbody>
</table>

Try that guy out :)