Template specialization is a feature in C++ that allows developers to define a different implementation of a template for a specific data type. This is especially useful when certain data types require unique handling or optimization compared to the general template definition.

The struct keyword in C++ allows a programmer to define a composite data type that groups variables of different data types under a single name. This makes it easier to organize related data. Initially in C, struct was used to define a simple group, but in C++ it's similar to a class.

Explicit template specialization allows for defining a different implementation of a template for a specific type or set of types. This is particularly useful when a general template definition would be correct for most types but not for a specific type or set of types. For instance, if most types can be handled with a general algorithm, but one type requires a more optimized or different approach, explicit specialization can be used for that type.

The continue statement, when encountered in a loop (like a while loop), will skip any subsequent statements in the current iteration and jump to the beginning of the next iteration.

Tail recursion optimization, often referred to as Tail Call Optimization (TCO), primarily serves to improve memory efficiency. When a recursive call is the last thing a function does (tail recursion), some languages can optimize it to reuse the current function's stack frame for the next function call. This can lead to significant savings in stack space, especially for deep recursive calls. It allows recursion-intensive algorithms to run without consuming as much memory or leading to a stack overflow.

The "&" (ampersand) operator is used to get the memory address of a variable in C++. For instance, if int x = 10;, then &x will give the memory address where the integer x is stored. The asterisk (*), on the other hand, is used for dereferencing.

In C++, the '/' operator is used for division. If used between two integers, it will perform integer division; with floats or doubles, it performs standard division.

When defining a struct in C++, the compiler will implicitly provide a default constructor if no constructors are explicitly defined. However, it won't automatically provide virtual destructors, overloaded operators, or private members without explicit definitions.

Using the goto statement without careful consideration can lead to "spaghetti code", which is a term for code that is tangled and difficult to follow or maintain due to excessive jumps.

The static_assert mechanism, combined with type traits, allows for compile-time checks. By using static_assert along with type traits like std::is_arithmetic, it's possible to generate clear, intentional compiler errors if a user tries to instantiate a template with a non-numeric type, thus providing instant feedback to the user.