What steps are needed to create servlets?

Create a class that implements the javax.servlet.Servlet interface or extends one of its subclasses, such as javax.servlet.http.HttpServlet.
Override necessary methods like init(), service(), destroy(), and for HttpServlet — doGet(), doPost(), and other do* methods.
Compile the servlet class.
Register the servlet in the deployment descriptor web.xml or use @WebServlet annotations for configuration.
Package the servlet and other web resources (HTML, JSP, etc.) into a standard web archive (.war).
Deploy the .war file on an application server or web container (e.g., Apache Tomcat, Jetty).

When using @WebServlet:

// Example of a simple servlet
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet("/hello") // Annotation for registering the servlet at URL "/hello"
public class HelloServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html"); // Set content type
        PrintWriter out = response.getWriter(); // Get writer object for response
        out.println("<html><body>"); // Write HTML response
        out.println("<h1>Hello from servlet!</h1>");
        out.println("</body></html>");
    }
}

When using web.xml:

<!-- Example of servlet registration in web.xml -->
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
             http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>HelloServlet</servlet-name> <!-- Unique servlet name -->
        <servlet-class>com.example.HelloServlet</servlet-class> <!-- Full class name of the servlet -->
    </servlet>

    <servlet-mapping>
        <servlet-name>HelloServlet</servlet-name> <!-- Registered servlet name -->
        <url-pattern>/hello_from_xml</url-pattern> <!-- URL pattern for accessing the servlet -->
    </servlet-mapping>

</web-app>