ALEKHINE'S DEFENCE

This is one of the most provocative defences to 1.e4. Black lures the white
pawns forward with the hope of eventually counterattacking the weakened white
position. Often the black king knight is chased all the way to the b6
square.

White may aggressively gain space with the aggressive four pawns attack
,but black gains a lead in development and should hold his own.

A sample line is 1.e4 Nf6 2.e5 Nd5 3.c4 Nb6 4.d4 d6 5.f4 dxe5 6.fxe5 Nc6
7.Be3 Bf5 8.Nc3 e6

White can continue aggressively with an early d5, but black has
counterattacking chances.

Alternatively, White can continue developing, in which case Black can do
likewise and put pressure on d4.

Another aggressive line is the Two pawns attack in which White attacks
black's knight no less than 4 times in sucession. 
In one line Black can win a pawn in exchange for a cramped game.

A sample line is 1.e4 Nf6 2.e5 Nd5 3.c4 Nb6 4.c5 Nd5 5.Bc4 e6 6.Nc3 Nxc3
7.bxc3 Bxc5 8.Qg4

Very often the black knight on d5 is driven back by c4 to b6 where it is
not so strong on the edge of the board, but at least attacks the pawn on
c4.

White may play in a more restrained position manner with 3.Nf3, but black
still can gain counterplay. Black usually plays d6 followed by Bg4 to pin
the white knight and put pressure on the centre. This is often followed by
e6 and Nc6.

Black will often strike in the centre with d5 at the right moment followed
by putting pressure on white's pawn at d4.

White can release the pressure on e5 by exchanging the epawn for the black
pawn on d6. Black sometimes has the choice between exd6, which allows for
speedy development of his king bishop, or cxd6 capturing towards the
centre.

In some lines Black can fianchetto his king bishop, though doing so in
some positions will lead to a cramped game.

White can play Bc4 instead of c4. Black often has the choice of whether to
defend the knight or retreat to b6 attacking the bishop.

With 3.Nc3 black can hold his own in the centre, by either exchanging
knights or by defending his knight with 3...e6 or 3...c6.

White's refusal to advance with 2.e5 may transpose in a Vienna, a Pirc or
a reversed philidor, and in any case should not lead to any problems for
Black.

1.e4 Nf6 2.Nc3 can lead to some uniquely Alekhine positions if black
answers with 2...d5, rather than 2...e5 (Vienna) or 2...d6(Pirc).

One sample line is 1.e4 Nf6 2.Nc3 d5 3.exd5 Nxd5 4.Bc4

Some interesting lines can occur if white plays 3.e5, e.g.
1.e4 Nf6 2.Nc3 d5 3.e5 Nfd7 4.d4 c5! or
1.e4 Nf6 2.Nc3 d5 3.e5 Nfd7 4.Nxd5 Nxe5 5.Ne3

A reversed Philidor arises after 1.e4 Nf6 2.d3 d5 3.Nd2 e5

All in all, a dynamic line for Black!