QR codes are two-dimensional symbols that most of the cameras can scan. Nowadays, the majority of phones and PCs are equipped by default with a QR code feature. Color codes enable the same physical space to convey more information by employing color in any pattern or design that attracts attention, such as a logo. When users capture a color or black-and-white image, the device decodes it and launches the device's browser to link to the URL included in the code.
If a lead generation strategy has been tried and proven before, an organization or individual with interest in a product, campaign, company concept, etc. means quality lead. To express interest, contact information, including an email address, a phone number, or even a social network account, is given. It's just lead if you don't know whether the lead generation method will clinch the deal or not.
A query is a particular request for data from a database. Queries, in particular in sophisticated database systems, make it simpler to discern patterns at a high level or make large-scale changes to data.