Bird Bath: Very simple but can be great as a focal point in a flowerbed. When it's hot and sunny, it's important the birds and insects like butterflies can get water and bathe. If it's a deep bath, put in a rock or a large cobble, so they don't fall in. Make sure that the birdbath is cleaned out on a regular basis.
The bird bath may be planted with plants like lilac and honeysuckle that will attract butterflies and bees, which are the insects that pollinate the flowers.
You can create an interesting garden by making the bird bath a focal point. The water brightens the garden because the sunlight catches the water.
Pebble Pool: It is child friendly, less formal and looks great with plantings around it. It is also easy to make and therefore it is less expensive than a self-contained unit. It works on the same principle of recycling the water. It should have a reservoir for a submersible pump to sit in a grid over the top of the supporting pebbles and plastic sheeting which funnels water back to the reservoir, depending on the fountain. The area is covered with a mixture of cobbles and gravel, but it is a good idea to test the pump before covering it with pebbles. The pool will go green naturally and doesn't need to be cleaned.
Self-Contained Fountain: More formal and no work is required. It works by recirculating the immersible pump in the base that pumps water around and around to create the gentle sound of running water, and lots of rippling reflections. The fountain will go green, so you may need to use chlorine or fountain cleaner you can get at a garden center. To keep it clear, soft water is best because it doesn't leave limescale on the ornament.
Potted Pond: It is ideal if you have a patio area or a balcony. It's semi-permanent, so if you move, you can take it with you. It tends to be ornate because the pot used can be dressed up. If you live in a colder area, it could freeze solid so you can move it closer to the house or bag it with bubble wrap.