Body language is a form of non-verbal communication which is signaled and interpreted subconsciously by the human mind.
Body language is the communication using facial gestures, postures and body movements. It is very useful in all sorts of human interactions and so it is also important while dating.
If the date is really important to you, tap into the non-verbal cues as well. There are signals; physical gestures, touching and movements that show your interest and disinterest, so you can hint your date accordingly. Besides, if you know how to read the body language of the other person, you can deduce for yourself if your date is going well or not.
There are certain things which you can do or observe to show or see interest. First and foremost, since most people while on a date feel nervous and conscious, you can ease your date in your company by mirroring your date's body language. If you and your date are comfortable in each other's company then half the battle is won. Then keep a constant eye contact, which shows your whole attention is captivated by your date. Lean towards your date while he/she is speaking, shows you are listening intently. If you are really smitten and also find that your date is comfortable with you, then touch subtly from time to time, it will definitely reveal your romantic intent towards him/her.
As equally as these positive gestures important, there are negative gestures too which you must avoid. To appear confident and calm is really important, but if you fiddle a lot, it will appear as if you are nervous. If you cross your arms across your chest, then it will appear that you are not interested. If you don't maintain an eye-contact, then it will appear your attention is not on your date, which is really the last thing your date would want to think or feel.
Hence, body language is as important as the verbal communication. Use the body language well to give signals as well as to interpret and know how your date is going.