Animation

The simplest of which is Scene.add. The object appears on the first frame without any animation:

class NoAnimation(Scene):
    def construct(self):
        square = Square()
        self.add(square))

Animation are used in conjunction with scene.Play

Fade

class AnimationFadeIn(Scene):
    def construct(self):
        square = Square()

        anno = TextMobject("Fade In")
        anno.shift(2 * DOWN)
        self.add(anno)
        self.play(FadeIn(square))

class AnimationFadeOut(Scene):
    def construct(self):
        square = Square()

        anno = TextMobject("Fade Out")
        anno.shift(2 * DOWN)
        self.add(anno)
        self.add(square)
        self.play(FadeOut(square))

class AnimationFadeInFrom(Scene):
    def construct(self):
        square = Square()
        for label, edge in zip(
            ["LEFT", "RIGHT", "UP", "DOWN"], [LEFT, RIGHT, UP, DOWN]
        ):
            anno = TextMobject(f"Fade In from {label}")
            anno.shift(2 * DOWN)
            self.add(anno)

            self.play(FadeInFrom(square, edge))
            self.remove(anno, square)

class AnimationFadeOutAndShift(Scene):
    def construct(self):
        square = Square()
        for label, edge in zip(
            ["LEFT", "RIGHT", "UP", "DOWN"], [LEFT, RIGHT, UP, DOWN]
        ):
            anno = TextMobject(f"Fade Out and shift {label}")
            anno.shift(2 * DOWN)
            self.add(anno)

            self.play(FadeOutAndShift(square, edge))
            self.remove(anno, square)

class AnimationFadeInFromLarge(Scene):
    def construct(self):
        square = Square()

        for factor in [0.1, 0.5, 0.8, 1, 2, 5]:
            anno = TextMobject(f"Fade In from large scale\_factor={factor}")
            anno.shift(2 * DOWN)
            self.add(anno)

            self.play(FadeInFromLarge(square, scale_factor=factor))
            self.remove(anno, square)

class AnimationFadeInFromPoint(Scene):
    def construct(self):
        square = Square()
        for i in range(-6, 7, 2):
            anno = TextMobject(f"Fade In from point {i}")
            anno.shift(2 * DOWN)
            self.add(anno)
            self.play(FadeInFromPoint(square, point=i))
            self.remove(anno, square)

Grow

class AnimationGrowFromEdge(Scene):
    def construct(self):

        for label, edge in zip(
            ["LEFT", "RIGHT", "UP", "DOWN"], [LEFT, RIGHT, UP, DOWN]
        ):
            anno = TextMobject(f"Grow from {label} edge")
            anno.shift(2 * DOWN)
            self.add(anno)
            square = Square()
            self.play(GrowFromEdge(square, edge))
            self.remove(anno, square)

class AnimationGrowFromCenter(Scene):
    def construct(self):
        square = Square()

        anno = TextMobject("Grow from center")
        anno.shift(2 * DOWN)
        self.add(anno)

        self.play(GrowFromCenter(square))

Diagonal Directions

You can combine cardinal directions to form diagonal animations

class AnimationFadeInFromDiagonal(Scene):
    def construct(self):
        square = Square()
        for diag in [UP + LEFT, UP + RIGHT, DOWN + LEFT, DOWN + RIGHT]:
            self.play(FadeInFrom(square, diag))

Note

You can also use the abbreviated forms like UL, UR, DL, DR. See Coordinates.