Types of Encounters
There are three types of encounters when dealing with law enforcement -- here is a brief overview of the encounters and what each one entails:

• Voluntary Encounter: Any officer may walk up to any person and strike up a conversation, much as any of us would. During this time, the officer may ask for anything; however, you are not required to give anything to the officer or, for that matter, even verbally respond to him.
  
  With a voluntary encounter, you are free to leave at any time by simply walking away from the officer. Of course, you are more than welcome to engage in conversation, the officer may simply be bored and talk about the weather. If you don't wish to engage in conversation and excuse yourself courteously and make sure, ask:
  
  "Am I free to leave, officer?"
  
  If the officer responds, "No." Immediately ask, "Am I being detained?" If the officer responds in the negative, continue to ask if you're free to leave and if you're being detained until he says yes to one or the other.
• Detainment (aka Terry Stop): Once you are being detained, you've been seized. Detainment occurs when a reasonable person believes that they are no longer free to leave. This is covered under the Delaware Criminal Code, Title 11, § 1902.
  
  An officer is allowed to detain someone when they have reasonable articulable suspicion -- that is, they can vocalize a reason -- that the person has, is or is about to commit a crime (State v. Miliany-Ojeda, - A.2d - (Del. Super. Ct. Feb. 18, 2004)).
  
  During this detainment an officer may do a Terry Pat Down or a plain-clothes feel. They may pat over the clothes to feel for weapons or contraband and seize those items for their safety for the duration of the encounter. In accordance with § 1903, the officer must return your weapon when the encounter ends.
  
  It is also during this point that the officer may demand identification and your business aboard (covered under § 1902). If you are not operating a motor vehicle, you are technically not required to produce physical identification, rather verbally stating your name and address would suffice.
  
  If, at the end of two hours, the officer's investigation yields no crimes, he must release you (§ 1902(c)).
• Arrest: The third type of encounter is an arrest. The officer has probable cause to believe you are guilty of a crime and may arrest you. Bear in mind that arrest is define as being restrained or by a large show of armed officers for example. It is not a process or going through booking.
  
  When arrested you are subject to a search incident to arrest. Essentially, before the officer places you in his cruiser, he's going to do a full search for weapons or contraband. If you were operating or were in control of a vehicle, it may also be towed into a police facility and and inventory search will be conducted in accordance with police procedure.
  
  If you are arrested, be sure to follow the tips outlines in the vehicular part of this essay.

With regards to rights violations, it's important to remember that, when you're detained, the officer must be able to articulate a reason why he thought you were, are or are about to commit a crime. Remember, open carrying is not a crime. If you are detained for this reason, there is a chance the detention is unlawful.

With all detentions, ask the officer for his business card. If you have a voice recorder, activate it (NOTE: I'm unsure as to the legalities of recording these encounters and will clarify in the future). As stated in the vehicular version of this essay, don't lie to law enforcement, don't resist and be respectful.

If you are concealing, you may wish to inform officer that you are licensed by the state and are currently armed. Remember that he has the right to disarm you for the duration of the detention.

Phrases to Remember

• Am I free to leave?
• Am I being detained?
• I don't consent to any searches.
• May I have your business card, officer?
• Officer, I have nothing to say until I confer with my attorney.

Stores and Security Guards
This is also another hot topic of discussion on the forums, so here's a few bits of information:

• A store (mall, shopping center), though open to the public, is still private property. Agents of the property owners (merchant, store supervisor, agent or employee of the store 18 years of age or older (§ 840)) may ask you to leave the premises for any reason. Do not remain on the property as you will be arrested for trespassing. You may request to speak to the manager.
• Searches and receipt checks are voluntary. They are store policy. Not law. You may refuse to show your receipt and the management has the right to ban you from the establishment.
• Stores may detain you if they have probable cause. If you've been paying attention, probable cause is required to arrest for police officers; however, for stores, they must believe you are guilty in order to detain you for law enforcement. This would include the actual concealing of merchandise and the belief that your intent was to deprive the store of the property without payment.
• If you are detained without probable cause, stores open themselves up to charges of Unlawful Imprisonment (§ 781).

I hope this document is helpful -- any comments or suggestions on additions, corrections or fixes are welcomed and solicited. Below, I've attached a video from the ACLU. I hate to use this as an example because, in most all cases, the people have something to hide; however, definitely watch it through.

A few things to add in light of a recent incident.

You are only required to identify yourself to an officer if you're being officially detained under § 1902.

If an officer asks you for identification and you don't wish to identify yourself, ask him if you're being detained. If he says no, ask if you're free to leave -- repeat this until you get an answer one way or another.

If he tells you you're being detained, you are not required to show a photo ID. The statute provides that you must give "the person's name, address, business abroad and destination." This does not need to be in the form of a government issued ID card. This is up to you if you wish to show your license.

If an officer tells you he's going to disarm you, it would be prudent to say, "I'm not resisting, but I do not consent to the seizure of my property." If you ARE being detained, he does have a right, under law, to disarm you -- at the end of the investigation, he must either arrest you or return your property. However, again, in order to detain you, he must have reasonable articulable suspicion that you have, are or are about to commit a crime. If you are told that you're being detained, you may wish to ask, "For which crime do you suspect me of to warrant a detention?"

To reiterate, explicitly refuse consent for any search or seizure. Ask if you're being detained. Do your best to keep your mouth shut. And, very importantly, always get the business card or badge number and name of the officer.

Now, this is also if the cop comes out of the gates with no professionalism or courtesy. You're, of course, probably going to be more likely to cooperate with a polite and inquisitive officer, but if you have an encounter with the former, you might be better of asserting and, more importantly, protecting your rights as vehemently as possible.

this is redundant, is it not? If I ask an officer if I'm being detained and he says "no", then without further questions, I will wish him a good day and walk off.

edited to add: this is how I will handle it, please feel free to handle your own situation as you see fit.

It is indeed redundant, but if you every find yourself in a situation where you need to defend your actions or pursue any legal avenues, you can say or write, the officer informed me that I was not being detained and that I was free to leave, but he continued to restrict my freedom of travel.