Soil types vary tremendously depending on region. Even within an average garden, it is possible for your soil pH and texture to change significantly. It is a good idea to test your soil pH in at least three locations within your garden and to visually appraise your soil type from list below.
Clay soil - Can be rolled into a ball on your hand with ease. It has a glossy sheen and characteristically holds water in the winter and dries out and cracks in hot months. Though typically fertile, clay soil can be difficult for some plants, especially those that can't take winter wet.
Acid soil - Is generally fertile and the greater majority of plants do well in an acid soil. Some plants (Camellia, Rhododendron, Calluna etc) need an acid soil and will die if grown in a chalky (alkaline) soil.
Sandy soil - Is very free draining and is generally good for coastal and most Mediterranean plants, which dislike excess moisture around their roots.
Moisture Loving plants do well in soil, which rarely, if ever, dries out.
Chalky Soil - Is Alkaline soil (the opposite of acid). It is typically free draining and nutrients are generally locked up in the soil, making it difficult for some plants to grow well. A small number of plants do well in very chalky soils, but most plants will take a small amount of soil alkalinity with little or no trouble.