Your baby's development is a progressive process. As one skill is learnt and accomplished, they will move onto learning another. Babies learn in the same way as most adults learn ? by seeing and doing something, then repeating the same thing over and over again! It is exciting to see your baby do something for the first time, and babies will often pick up on the animated delight that parent's will display at their achievements. This encourages them to repeat the action again (and again!)
Most babies will experience 'phases'. Sometimes they will appear to be developing very quickly, and at other times nothing much can seem to be happening. Your baby may make quick progress in their speech development, but be slower in their gross motor development (like walking). Others may steadily develop fine motor skills (like grasping rattles and other objects) but appear slow in developing their speech.
Try not to compare your baby's development with other babies (as hard as this can be at times). It is much easier if you can simply enjoy your baby for where they are at, and not waste time worrying about where you would like them to be. Milestones can be exciting to reach, but they can also bring up emotions of grief for the 'loss of your little baby' in a sense, and achievements can sometimes bring up mixed feelings of joy and regret. (For example.... "Oh look they are walking...Oh no they are running away!")
NOTE: If you do feel very concerned about your baby's development being noticeably slow, or they are behind in two or more areas of development, seek the advice of your early childhood nurse or local doctor. Early detection and early intervention of true developmental delay can have a significant impact on a baby's potential for normal development.
The following are 'average' achievements for babies. Remember that the range of 'normal' is extremely wide, and can deviate in weeks and months from these expectations (and still be normal).
At birth