Two basic options, along with two more specific variations.
Wrap a series of buttons with .btn in .btn-group.
.btn
.btn-group
<div class="btn-group"> <button class="btn">Left</button> <button class="btn">Middle</button> <button class="btn">Right</button> </div>
Combine sets of <div class="btn-group"> into a <div class="btn-toolbar"> for more complex components.
<div class="btn-group">
<div class="btn-toolbar">
<div class="btn-toolbar"> <div class="btn-group"> ... </div> </div>