You're allowed to take bags with you as you board an aircraft, but what those bags contain is restricted. Anything that could be used as a weapon is not allowed. So, for example, as the "Road and Travel Magazine" website points out, metal scissors with pointed tips and army knives aren't going to be allowed in your carry-on baggage, so it's in your best interest to remove these items ahead of time. Other prohibited items include firearms, tools such as hammers and crowbars, flammable items, disabling chemicals including liquid bleach and spray paint and explosive materials such as fireworks, as described by the TSA website.
Liquid items---such cologne and some make-up items---are considered a potential threat by airlines, since liquids can be used as bomb components by terrorists. The amount of liquid you may bring aboard an aircraft will vary according to each airline, but in the United States, the rules set out by the TSA limit liquids to bottles that can be contained in a one-quart bag per passenger. This bag must be clear so security staff can check it, and have a zip top. In the bag, you can place multiple small bottles, but each liquid container can't be more than 100 ml in volume, as stated by the TSA website.
Certain liquids aren't affected by these restrictions. Liquids in medicines and those used for consumption by babies, along with breast milk, must be declared to airline staff as you board the aircraft, but don't have to be placed in the zip-top bag and aren't limited to 100 ml or less.
Adult travellers will need to have the appropriate documents on their person before they can board an aircraft. This means that before trying to board, you should get your boarding pass for the flight. This pass can be obtained either beforehand via the airline's website, over the airport counter or by using a self-service kiosk located at the airport. You'll also want to have your passport---or another form of photo identification---on hand at all times, since security may wish to check this.
If you've got kids with you, they won't need to produce I.D., as noted by the TSA website, but will need to have a boarding pass.
