what is the relevance of the concept of "par value"?

Answer 1

It depends on what you're asking about. Par value of shares is losing its relevance. Par value of a bond is very relevant.

Par value is the face value of a security or financial instrument. The par value of a common stock is the nominal value assigned by a corporate charter, and has no specific financial relevance after the issue date. Par value of an equity (a stock) is a somewhat archaic concept. Increasingly, companies are moving towards shares with no par value. The par value of a debt security, for example a bond, is very relevant, as that is the price that will be paid the bondholder at maturity. The bond coupon interest payable semi-annually is a percentage of a bond's par value. Preferred stock dividends normally are stated as a percentage of the assigned par value, but also may be determined by auction bidding at periodic intervals. Par value is unrelated to market value, which is influenced more by market pricing, Yield on the securities offered for sale, Net Asset Value , and prices of comparable issues in the secondary market.

Answer 2

When a company is incorporated the initial value of the stock is the par value. That is essentially the stock's book value.