An attorney at law (also known simply as an attorney or lawyer in the United States is a person licensed to practice law by the highest court of a state or other jurisdiction. Alternate terms include attorney-at-law and attorney and counselor (or counsellor) at law.
The American legal system has a united (or fused) legal profession, and does not draw a distinction between lawyers who plead in court and those who do not. Many other common law jurisdictions, as well as some civil law jurisdictions, have a separation, such as the solicitor and barrister advocate split in the United Kingdom and the advocate civil law notary split in France. There is also no delegation of routine work to notaries public or their civil law equivalent.
Comparison: attorney in fact and attorney at law
Broadly speaking, an "attorney" is one who acts on behalf of another person in some capacity. For example, an "attorney-in-fact" is a kind of agent who acts on behalf of another person, typically with respect to business, property, or personal matters, and who does not have to be licensed to practice law or to have any other license from the government. The term power of attorney refers to the authority of an attorney-in-fact to act in the name of another person, and to the signed document which is evidence of such authority.
By contrast an attorney at law, or lawyer, is a person trained and licensed to practice law to represent clients in legal matters (both in and out of court), and to give legal advice. In the United States, the term attorney, standing alone, is generally intended to have this meaning (and not to mean "attorney in fact").
The term Attorney General is used to designate the chief law enforcement officer of a state or other political jurisdiction. The attorney general is a lawyer who represents the government, prosecutes criminal cases, defends the government from lawsuits against it, and brings civil lawsuits to enforce consumer protection and antitrust laws.