  We present here the extended-object approach for the explanation and
calculation of the self-force phenomenon. In this approach, one considers a
charged extended object of a finite size $\epsilon$ that accelerates in a
nontrivial manner, and calculates the total force exerted on it by the
electromagnetic field (whose source is the charged object itself). We show that
at the limit $\epsilon \to 0$ this overall electromagnetic field yields a
universal result, independent on the object's shape, which agrees with the
standard expression for the self force acting on a point-like charge. This
approach has already been considered by many authors, but previous analyses
ended up with expressions for the total electromagnetic force that include
$O(1/\epsilon)$ terms which do not have the form required by
mass-renormalization. (In the special case of a spherical charge distribution,
this $\propto 1/\epsilon $ term was found to be 4/3 times larger than the
desired quantity.) We show here that this problem was originated from a too
naive definition of the notion of ''total electromagnetic force'' used in
previous analyses. Based on energy-momentum conservation combined with proper
relativistic kinematics, we derive here the correct notion of total
electromagnetic force. This completely cures the problematic $O(1/\epsilon)$
term, for any object's shape, and yields the correct self force at the limit
$\epsilon \to 0$. In particular, for a spherical charge distribution, the above
''4/3 problem'' is resolved.
