what is the purpose of all of these migration fields?

I have created migration of jobs table but schema has fields i don't know about . I want to know purpose of each fields in this schema

 Schema::create('jobs', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->string('queue')->index();
            $table->longText('payload');
            $table->unsignedTinyInteger('attempts');
            $table->unsignedInteger('reserved_at')->nullable();
            $table->unsignedInteger('available_at');
            $table->unsignedInteger('created_at');
        });

I want to know complete functionality of every filed

via Chebli Mohamed