Terminology
A "smith" of any type is one who shapes metal pieces, often using a forge or mould, into useful objects or to be part of a more complex structure. Locksmithing, as its name implies, is the assembly and designing of locks and their respective keys.

 Work
Although fitting of keys to replace lost keys to automobiles and homes and the changing of keys for homes and businesses to maintain security are still an important part of locksmithing, locksmiths today are primarily involved in the installation of higher quality locksets and the design, implementation and management of keying and key control systems. Most locksmiths also do electronic lock servicing, such as making keys for transponder-equipped vehicles and the implementation and application of access control systems protecting individuals and assets for many large institutions. In terms of physical security, a locksmith's work frequently involves making a determination of the level of risk to an individual or institution and then recommending and implementing appropriate combinations of equipment and policies to create "security layers" which exceed the reasonable gain to an intruder or attacker. The more different security layers are implemented, the more the requirement for additional skills and knowledge and tools to defeat them all. But because each layer comes at an expense to the customer, the application of appropriate levels without exceeding reasonable costs to the customer is often very important and requires a skilled and knowledgeable locksmith to determine.

Employment
Locksmiths may be commercial (working out of a storefront), mobile (working out of a vehicle), institutional (employed by an institution) or investigational (forensic locksmiths) or may specialize in one aspect of the skill, such as an automotive lock specialist, a master key system specialist or a safe technician. Many (not all) are also security consultants, but not every security consultant has the skills and knowledge of a locksmith. Locksmiths are frequently certified in specific skill areas or to a level of skill within the trade. This is separate from certificates of completion of training courses. In determining skill levels, certifications from manufacturers or locksmith associations are usually more valid criteria than certificates of completion. Some locksmiths decide to call themselves "Master Locksmiths" whether they are fully trained or not, and some training certificates appear quite authoritative. It may be noted, however, that in some countries a particular level of qualification or membership of an organization is required before one can adopt the term Master Locksmith.

Locks
In the general case, a lock will not keep out an absolutely determined intruder with unlimited resources, skills, knowledge and time. However, even a minimal lock can delay a typical intruder for a time, and the disturbance generated in circumventing a high-quality lock, for example by breaking windows or doors, can deter many attackers, causing them to direct their attacks against weaker targets.

When combined with secure containers, or document destruction systems, or electronic access or alarm systems, locks can provide much higher levels of security. Some locksmiths possess these skills, and others form business relationships with companies or individuals with these specialties