Heam and non-haem (or heme and non-heme in American English: The former, found in animal flesh, is already in the form of haemoglobin and is very easily absorbed. The latter, found in vegetables, grains, nuts, seeds, legume and dairy, is less easily absorbed. Animal flesh also contains non-haem iron as the animals will have been consuming plants, such as grass and grains.
Eating a wide variety of food should supply enough iron for most of us. However, that may not be the case if you’ve been diagnosed with anaemia, or have additional requirements associated with blood loss or a pregnancy, in which there is a greater requirement for blood.