7 to 9 months Chunkier Chews:The move to solids progresses rapidly now. Baby begins to chew with an up and down movement of the jaw, replacing the predominately sucking motion of earlier. This, plus the ability to grasp and the direct propulsion of grasped objects to the mouth tells you he is ready for finger food. To begin with, he has a palmer grasp (e.g. smashing fistfuls of cereal somewhere in the vicinity of his mouth!) so the shape of the finger foods you offer is important. Teething biscuits, toast, bagels and crackers are easiest for him to hold. It's doubtful he'll get too much down yet, so don't count it as contributing to his nutrient intake. By the end of this stage his grasp will be more digital and he'll be able to better manipulate little things like Cheerios and green peas.
Now he is ready for, and needs, thicker, chunkier foods. Soft mashed but not strained food should be offered to him. In an important study by two researchers, Illingworth and Lister, it was shown that it was critical to offer harder to chew foods at this developmental age. To not do so resulted in real difficulties in their acceptance later on.
Once your baby seems to be getting more and more of his nutrition from solids and less from you or formula, it becomes important to replace the nutrients they are no longer receiving from those liquids. Food to introduce now should offer some protein and calcium.
Foods to add at 7 to 9 months: mashed fruits and vegetables (either soft ripe or cooked), plain yogurt, tofu, finger food, vitamin C rich 100% juice in a sippy cup.